Systems and methods for controlling velocity of a displacement member of a surgical stapling and cutting instrument

ABSTRACT

A motorized surgical instrument is disclosed. The surgical instrument includes a displacement member, a motor coupled to the displacement member, the motor operable to translate the displacement member, a control circuit coupled to the motor, and a position sensor coupled to the control circuit. The control circuit is configured to receive a position output of the position sensor indicative of at least one position of the displacement member and control velocity of the motor to translate the displacement member at a plurality of velocities corresponding to the position output. Each of the plurality of velocities is maintained in a predetermined zone.

TECHNICAL FIELD

The present disclosure relates to surgical instruments and, in variouscircumstances, to surgical stapling and cutting instruments and staplecartridges therefor that are designed to staple and cut tissue.

BACKGROUND

In a motorized surgical stapling and cutting instrument it may be usefulto control the velocity of a cutting member or to control thearticulation velocity of an end effector. Velocity of a displacementmember may be determined by measuring elapsed time at predeterminedposition intervals of the displacement member or measuring the positionof the displacement member at predetermined time intervals. The controlmay be open loop or closed loop. Such measurements may be useful toevaluate tissue conditions such as tissue thickness and adjust thevelocity of the cutting member during a firing stroke to account for thetissue conditions. Tissue thickness may be determined by comparingexpected velocity of the cutting member to the actual velocity of thecutting member. In some situations, it may be useful to articulate theend effector at a constant articulation velocity. In other situations,it may be useful to drive the end effector at a different articulationvelocity than a default articulation velocity at one or more regionswithin a sweep range of the end effector.

During use of a motorized surgical stapling and cutting instrument it ispossible that the force to fire experienced by the cutting member orfiring member may be substantially different based on the location ofthe cutting member or firing during the firing stroke. Generally, thefirst zone is the most highly loaded and the last zone is the leasthighly loaded. Therefore, it may be desirable to define the firingstroke into distinct zones with varying cutting member advancementvelocity in each zone based on the force to fire load experienced by thefiring system and to vary the firing velocity of the cutting memberbased on the position of the cutting member along the firing stroke. Itwould be desirable to set the firing velocity at the slowest velocityduring in the first zone where the cutting member or firing member isunder the highest load and increase the velocity in each subsequentzone. It may be desirable to set the velocity in the first zone bydetermining the tissue thickness or tissue gap by measuring anycombination of current through the motor, time to advance the cuttingmember to a predefined distance, displacement of the cutting member overa predefined time, or any proxy for load on the motor.

SUMMARY

In one aspect, the present disclosure provides a surgical instrument.The surgical instrument comprises a displacement member; a motor coupledto the displacement member, the motor operable to translate thedisplacement member; a control circuit coupled to the motor; and aposition sensor coupled to the control circuit; wherein the controlcircuit is configured to: receive a position output of the positionsensor indicative of at least one position of the displacement member;and control velocity of the motor to translate the displacement memberat a plurality of velocities corresponding to the position output,wherein each of the plurality of velocities is maintained in apredetermined zone.

In another aspect, the surgical instrument comprises a displacementmember; a motor coupled to the displacement member, the motor operableto translate the displacement member; a control circuit coupled to themotor; and a position sensor coupled to the control circuit; wherein thecontrol circuit is configured to: receive a position output of theposition sensor indicative of at least one position of the displacementmember; and drive the motor to translate the displacement member at adisplacement member velocity corresponding to the position of thedisplacement member.

In another aspect, the surgical instrument comprises a displacementmember; a motor coupled to the displacement member, the motor operableto translate the displacement member; a control circuit coupled to themotor; and a position sensor coupled to the control circuit; wherein thecontrol circuit is configured to: receive a position output of theposition sensor indicative of at least one position of the displacementmember along the distance between the proximal position and the distalposition; and drive the motor at a plurality of duty cyclescorresponding to the position output, wherein each of the plurality ofduty cycles is maintained in a predetermined zone between the proximalposition and the distal position.

FIGURES

The novel features of the aspects described herein are set forth withparticularity in the appended claims. These aspects, however, both as toorganization and methods of operation may be better understood byreference to the following description, taken in conjunction with theaccompanying drawings.

FIG. 1 is a perspective view of a surgical instrument that has aninterchangeable shaft assembly operably coupled thereto according to oneaspect of this disclosure.

FIG. 2 is an exploded assembly view of a portion of the surgicalinstrument of FIG. 1 according to one aspect of this disclosure.

FIG. 3 is an exploded assembly view of portions of the interchangeableshaft assembly according to one aspect of this disclosure.

FIG. 4 is an exploded view of an end effector of the surgical instrumentof FIG. 1 according to one aspect of this disclosure.

FIGS. 5A-5B is a block diagram of a control circuit of the surgicalinstrument of FIG. 1 spanning two drawing sheets according to one aspectof this disclosure.

FIG. 6 is a block diagram of the control circuit of the surgicalinstrument of FIG. 1 illustrating interfaces between the handleassembly, the power assembly, and the handle assembly and theinterchangeable shaft assembly according to one aspect of thisdisclosure.

FIG. 7 illustrates a control circuit configured to control aspects ofthe surgical instrument of FIG. 1 according to one aspect of thisdisclosure.

FIG. 8 illustrates a combinational logic circuit configured to controlaspects of the surgical instrument of FIG. 1 according to one aspect ofthis disclosure.

FIG. 9 illustrates a sequential logic circuit configured to controlaspects of the surgical instrument of FIG. 1 according to one aspect ofthis disclosure.

FIG. 10 is a diagram of an absolute positioning system of the surgicalinstrument of FIG. 1 where the absolute positioning system comprises acontrolled motor drive circuit arrangement comprising a sensorarrangement according to one aspect of this disclosure.

FIG. 11 is an exploded perspective view of the sensor arrangement for anabsolute positioning system showing a control circuit board assembly andthe relative alignment of the elements of the sensor arrangementaccording to one aspect of this disclosure.

FIG. 12 is a diagram of a position sensor comprising a magnetic rotaryabsolute positioning system according to one aspect of this disclosure.

FIG. 13 is a section view of an end effector of the surgical instrumentof FIG. 1 showing a firing member stroke relative to tissue graspedwithin the end effector according to one aspect of this disclosure.

FIG. 14 illustrates a block diagram of a surgical instrument programmedto control distal translation of a displacement member according to oneaspect of this disclosure.

FIG. 15 illustrates a diagram plotting two example displacement memberstrokes executed according to one aspect of this disclosure.

FIG. 16 depicts two diagrams illustrating the force to close (FTC) theanvil of the surgical instrument of FIG. 1 as a function of closurestroke displacement (d) and the force to fire (FTF) the surgicalinstrument of FIG. 1 as a function of time according to one aspect ofthis disclosure.

FIG. 17 illustrates a logic flow diagram showing an example of a processof a control program or logic configuration that may be executed by asurgical instrument (e.g., a control circuit of a surgical instrument)to implement an I-beam firing stroke according to one aspect of thisdisclosure.

FIG. 18 is a diagram illustrating velocity (v) of the I-beam as afunction of firing stroke displacement (d) according to one aspect ofthis disclosure.

FIG. 19A is a logic flow diagram representing a firing control programor logic configuration according to one aspect of this disclosure.

FIG. 19B is a logic flow diagram representing a firing control programor logic configuration according to one aspect of this disclosure.

FIG. 20 depicts two diagrams illustrating the force to fire (FTF) thesurgical instrument of FIG. 1 as a function of time, and motor dutycycle (velocity %) of a motor driving the I-beam as a function of I-beamdisplacement (d) according to one aspect of this disclosure.

FIG. 21 depicts two diagrams illustrating motor duty cycle (velocity %)of a motor driving the I-beam as a function of I-beam displacement (d),and Pulse-Width Modulation (PWM) as a function of the I-beamdisplacement (d) according to one aspect of this disclosure.

FIG. 22 depicts two diagrams illustrating the force to close the anvilof the surgical instrument of FIG. 1 as a function of time and the forceto fire the surgical instrument of FIG. 1 as a function of timeaccording to one aspect of this disclosure.

FIG. 23 illustrates an anvil according to one aspect of this disclosure.

DESCRIPTION

Applicant of the present application owns the following patentapplications filed Jun. 20,2017 and which are each herein incorporatedby reference in their respective entireties:

U.S. patent application Ser. No. 15/627,998, titled CONTROL OF MOTORVELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON ANGLE OFARTICULATION, by inventors Frederick E. Shelton, IV et al., filed Jun.20, 2017, now U.S. Pat. No. 10,390,841.

U.S. patient application Ser. No. 15/628,09, titled SURGICAL INSTRUMENTWITH VARIABLE DURATION TRIGGER ARRANGEMENT, by inventors Frederick E.Shelton, IV et al., filed Jun. 20, 2017, now U.S. patent applicationSer. No. 2018/0360443.

U.S. patent application Ser. No. 15/628/036, titled SYSTEMS AND METHODSFOR CONTROLLING DISPLACEMENT MEMBER MOTION OF A SURGICAL STAPLING ANDCUTTING INSTRUMENT, by inventors Frederick E. Shelton, IV et al., filedJun. 20, 2017, now U.S. Patent Application Publication No. 2018/0360445.

U.S. patent application Ser. No. 15/628050, titled SYSTEMS AND METHODSFOR CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTINGINSTRUMENT ACCORDING TO ARTICULATION ANGLE OF END EFFECTOR, by inventorsFrederick E. Shelton, IV et al., filed Jun. 20, 2017, now U.S. patentapplication No. 2018/0360446.

U.S. patent application Ser. No. 15/628,075, titled SYSTEMS AND METHODSFOR CONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTINGINSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20,2017, now U.S. Pat. No. 10,624,633.

U.S. patent application Ser. No. 15/628,154, titled SURGICAL INSTRUMENTHAVING CONTROLLABLE ARTICULATION VELOCITY, by inventors Frederick E.Shelton, IV et al., filed Jun. 20, 2017, now U.S. Patent ApplicationPublication No. 2018/030456.

U.S. patent application Ser. No. 15/628,162, titled SYSTEMS AND METHODSFOR CONTROLLING DISPLACEMENT MEMBER VELOCITY FOR A SURGICAL INSTRUMENT,by inventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017, nowU.S. Pat. No. 10,646,220.

U.S. patent application Ser. No. 15/628,168, titled CONTROL OF MOTORVELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENT BASED ON ANGLE OFARTICULATION, by inventors Frederick E. Shelton, IV et al., filed Jun.20, 2017, now U.S. Pat. No. 10,327,767.

U.S. patent application Ser. No. 15/628,175, titled TECHNIQUES FORADAPTIVE CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTINGINSTRUMENT, by inventors Frederick E. Shelton, IV et al., filed Jun. 20,2017, now U.S. Patent Application Publication No. 2018/0360452.

U.S. patent application Ser. No. 15/628,045, titled TECHNIQUES FORCLOSED LOOP CONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTINGINSTRUMENT, by inventors Raymond E. Parfett et al., filed Jun. 20, 2017,now U.S. Pat. No. 10,307,170.

U.S. patent application Ser. No. 15/628,053, titled CLOSED LOOP FEEDBACKCONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENTBASED ON MAGNITUDE OF VELOCITY ERROR MEASUREMENTS, by inventors RaymondE. Parfett et al., filed Jun. 20, 2017, now U.S. Patent ApplicationPublication No. 2018/0360471.

U.S. Patent Application Ser. No. 15/628,060, titled CLOSED LOOP FEEDBACKCONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENTBASED ON MEASURED TIME OVER A SPECIFIED DISPLACEMENT DISTANCE, byinventors Jason L. Harris et al., filed Jun. 20, 2017, now U.S. PatentApplication Publication No. 2018/0360472.

U.S. patent application Ser. No. 15/628,067, titled CLOSED LOOP FEEDBACKCONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENTBASED ON MEASURED DISPLACEMENT DISTANCE TRAVELED OVER A SPECIFIED TIMEINTERVAL, by inventors Frederick E. Shelton, IV et al., filed Jun. 20,2017, now U.S. Patent Application Publication No. 2018/0360473.

U.S. patent application Ser. No. 15/628,072, titled CLOSED LOOP FEEDBACKCONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENTBASED ON MEASURED TIME OVER A SPECIFIED NUMBER OF SHAFT ROTATIONS, byinventors Frederick E. Shelton, IV et al., filed Jun. 20, 2017, now U.S.Patent Application Publication No. 2018/0360454.

U.S. patent application Ser. No. 15/628,029, titled SYSTEMS AND METHODSFOR CONTROLLING DISPLAYING MOTOR VELOCITY FOR A SURGICAL INSTRUMENT, byinventors Jason L. Harris et al., filed Jun. 20, 2017, now U.S. Pat. No.10,368,864.

U.S. patent application Ser. No. 15/628,077, titled SYSTEMS AND METHODSFOR CONTROLLING MOTOR SPEED ACCORDING TO USER INPUT FOR A SURGICALINSTRUMENT, by inventors Jason L. Harris et al., filed Jun. 20, 2017,now U.S. Patent Application Publication No. 2018/0360448.

U.S. patent application Ser. No. 15/628,115, titled CLOSED LOOP FEEDBACKCONTROL OF MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTING INSTRUMENTBASED ON SYSTEM CONDITIONS, by inventors Frederick E. Shelton, IV etal., filed Jun. 20, 2017, now U.S. Patent Application Publication No.2018/0360455.

U.S. Design Patent Application Ser. No. 29/608,238, titled GRAPHICALUSER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Jason L.Harris et al., filed Jun. 20, 2017, now U.S. Pat. No. D879,809.

U.S. Design Patent Application Ser. No. 29/608/231, titled GRAPHICALUSER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors Jason L.Harris et al., filed Jun. 20, 2017, now U.S. Pat. No. D879,808.

U.S. Design Patent Application Ser. No. 29/608,246, titled GRAPHICALUSER INTERFACE FOR A DISPLAY OR PORTION THEREOF, by inventors FrederickE. Shelton, IV et al., filed Jun. 20, 2017, now U.S. Pat. No. D890,784.

Certain aspects are shown and described to provide an understanding ofthe structure, function, manufacture, and use of the disclosed devicesand methods. Features shown or described in one example may be combinedwith features of other examples and modifications and variations arewithin the scope of this disclosure.

The terms “proximal” and “distal” are relative to a clinicianmanipulating the handle of the surgical instrument where “proximal”refers to the portion closer to the clinician and “distal” refers to theportion located further from the clinician. For expediency, spatialterms “vertical,” “horizontal,” “up,” and “down” used with respect tothe drawings are not intended to be limiting and/or absolute, becausesurgical instruments can used in many orientations and positions.

Example devices and methods are provided for performing laparoscopic andminimally invasive surgical procedures. Such devices and methods,however, can be used in other surgical procedures and applicationsincluding open surgical procedures, for example. The surgicalinstruments can be inserted into a through a natural orifice or throughan incision or puncture hole formed in tissue. The working portions orend effector portions of the instruments can be inserted directly intothe body or through an access device that has a working channel throughwhich the end effector and elongated shaft of the surgical instrumentcan be advanced.

FIGS. 1-4 depict a motor-driven surgical instrument 10 for cutting andfastening that may or may not be reused. In the illustrated examples,the surgical instrument 10 includes a housing 12 that comprises a handleassembly 14 that is configured to be grasped, manipulated, and actuatedby the clinician. The housing 12 is configured for operable attachmentto an interchangeable shaft assembly 200 that has an end effector 300operably coupled thereto that is configured to perform one or moresurgical tasks or procedures. In accordance with the present disclosure,various forms of interchangeable shaft assemblies may be effectivelyemployed in connection with robotically controlled surgical systems. Theterm “housing” may encompass a housing or similar portion of a roboticsystem that houses or otherwise operably supports at least one drivesystem configured to generate and apply at least one control motion thatcould be used to actuate interchangeable shaft assemblies. The term“frame” may refer to a portion of a handheld surgical instrument. Theterm “frame” also may represent a portion of a robotically controlledsurgical instrument and/or a portion of the robotic system that may beused to operably control a surgical instrument. Interchangeable shaftassemblies may be employed with various robotic systems, instruments,components, and methods disclosed in U.S. Pat. No. 9,072,535, entitledSURGICAL STAPLING INSTRUMENTS WITH ROTATABLE STAPLE DEPLOYMENTARRANGEMENTS, which is herein incorporated by reference in its entirety.

FIG. 1 is a perspective view of a surgical instrument 10 that has aninterchangeable shaft assembly 200 operably coupled thereto according toone aspect of this disclosure. The housing 12 includes an end effector300 that comprises a surgical cutting and fastening device configured tooperably support a surgical staple cartridge 304 therein. The housing 12may be configured for use in connection with interchangeable shaftassemblies that include end effectors that are adapted to supportdifferent sizes and types of staple cartridges, have different shaftlengths, sizes, and types. The housing 12 may be employed with a varietyof interchangeable shaft assemblies, including assemblies configured toapply other motions and forms of energy such as, radio frequency (RF)energy, ultrasonic energy, and/or motion to end effector arrangementsadapted for use in connection with various surgical applications andprocedures. The end effectors, shaft assemblies, handles, surgicalinstruments, and/or surgical instrument systems can utilize any suitablefastener, or fasteners, to fasten tissue. For instance, a fastenercartridge comprising a plurality of fasteners removably stored thereincan be removably inserted into and/or attached to the end effector of ashaft assembly.

The handle assembly 14 may comprise a pair of interconnectable handlehousing segments 16, 18 interconnected by screws, snap features,adhesive, etc. The handle housing segments 16, 18 cooperate to form apistol grip portion 19 that can be gripped and manipulated by theclinician. The handle assembly 14 operably supports a plurality of drivesystems configured to generate and apply control motions tocorresponding portions of the interchangeable shaft assembly that isoperably attached thereto. A display may be provided below a cover 45.

FIG. 2 is an exploded assembly view of a portion of the surgicalinstrument 10 of FIG. 1 according to one aspect of this disclosure. Thehandle assembly 14 may include a frame 20 that operably supports aplurality of drive systems. The frame 20 can operably support a “first”or closure drive system 30, which can apply closing and opening motionsto the interchangeable shaft assembly 200. The closure drive system 30may include an actuator such as a closure trigger 32 pivotally supportedby the frame 20. The closure trigger 32 is pivotally coupled to thehandle assembly 14 by a pivot pin 33 to enable the closure trigger 32 tobe manipulated by a clinician. When the clinician grips the pistol gripportion 19 of the handle assembly 14, the closure trigger 32 can pivotfrom a starting or “unactuated” position to an “actuated” position andmore particularly to a fully compressed or fully actuated position.

The handle assembly 14 and the frame 20 may operably support a firingdrive system 80 configured to apply firing motions to correspondingportions of the interchangeable shaft assembly attached thereto. Thefiring drive system 80 may employ an electric motor 82 located in thepistol grip portion 19 of the handle assembly 14. The electric motor 82may be a DC brushed motor having a maximum rotational speed ofapproximately 25,000 RPM, for example. In other arrangements, the motormay include a brushless motor, a cordless motor, a synchronous motor, astepper motor, or any other suitable electric motor. The electric motor82 may be powered by a power source 90 that may comprise a removablepower pack 92. The removable power pack 92 may comprise a proximalhousing portion 94 configured to attach to a distal housing portion 96.The proximal housing portion 94 and the distal housing portion 96 areconfigured to operably support a plurality of batteries 98 therein.Batteries 98 may each comprise, for example, a Lithium Ion (LI) or othersuitable battery. The distal housing portion 96 is configured forremovable operable attachment to a control circuit board 100, which isoperably coupled to the electric motor 82. Several batteries 98connected in series may power the surgical instrument 10. The powersource 90 may be replaceable and/or rechargeable. A display 43, which islocated below the cover 45, is electrically coupled to the controlcircuit board 100. The cover 45 may be removed to expose the display 43.

The electric motor 82 can include a rotatable shaft (not shown) thatoperably interfaces with a gear reducer assembly 84 mounted in meshingengagement with a with a set, or rack, of drive teeth 122 on alongitudinally movable drive member 120. The longitudinally movabledrive member 120 has a rack of drive teeth 122 formed thereon formeshing engagement with a corresponding drive gear 86 of the gearreducer assembly 84.

In use, a voltage polarity provided by the power source 90 can operatethe electric motor 82 in a clockwise direction wherein the voltagepolarity applied to the electric motor by the battery can be reversed inorder to operate the electric motor 82 in a counter-clockwise direction.When the electric motor 82 is rotated in one direction, thelongitudinally movable drive member 120 will be axially driven in thedistal direction “DD.” When the electric motor 82 is driven in theopposite rotary direction, the longitudinally movable drive member 120will be axially driven in a proximal direction “PD.” The handle assembly14 can include a switch that can be configured to reverse the polarityapplied to the electric motor 82 by the power source 90. The handleassembly 14 may include a sensor configured to detect the position ofthe longitudinally movable drive member 120 and/or the direction inwhich the longitudinally movable drive member 120 is being moved.

Actuation of the electric motor 82 can be controlled by a firing trigger130 that is pivotally supported on the handle assembly 14. The firingtrigger 130 may be pivoted between an unactuated position and anactuated position.

Turning back to FIG. 1, the interchangeable shaft assembly 200 includesan end effector 300 comprising an elongated channel 302 configured tooperably support a surgical staple cartridge 304 therein. The endeffector 300 may include an anvil 306 that is pivotally supportedrelative to the elongated channel 302. The interchangeable shaftassembly 200 may include an articulation joint 270. Construction andoperation of the end effector 300 and the articulation joint 270 are setforth in U.S. Patent Application Publication No. 2014/0263541, entitledARTICULATABLE SURGICAL INSTRUMENT COMPRISING AN ARTICULATION LOCK, whichis herein incorporated by reference in its entirety. The interchangeableshaft assembly 200 may include a proximal housing or nozzle 201comprised of nozzle portions 202, 203. The interchangeable shaftassembly 200 may include a closure tube 260 extending along a shaft axisSA that can be utilized to close and/or open the anvil 306 of the endeffector 300.

Turning back to FIG. 1, the closure tube 260 is translated distally(direction “DD”) to close the anvil 306, for example, in response to theactuation of the closure trigger 32 in the manner described in theaforementioned reference U.S. Patent Application Publication No.2014/0263541. The anvil 306 is opened by proximally translating theclosure tube 260. In the anvil-open position, the closure tube 260 ismoved to its proximal position.

FIG. 3 is another exploded assembly view of portions of theinterchangeable shaft assembly 200 according to one aspect of thisdisclosure. The interchangeable shaft assembly 200 may include a firingmember 220 supported for axial travel within the spine 210. The firingmember 220 includes an intermediate firing shaft 222 configured toattach to a distal cutting portion or knife bar 280. The firing member220 may be referred to as a “second shaft” or a “second shaft assembly”.The intermediate firing shaft 222 may include a longitudinal slot 223 ina distal end configured to receive a tab 284 on the proximal end 282 ofthe knife bar 280. The longitudinal slot 223 and the proximal end 282may be configured to permit relative movement there between and cancomprise a slip joint 286. The slip joint 286 can permit theintermediate firing shaft 222 of the firing member 220 to articulate theend effector 300 about the articulation joint 270 without moving, or atleast substantially moving, the knife bar 280. Once the end effector 300has been suitably oriented, the intermediate firing shaft 222 can beadvanced distally until a proximal sidewall of the longitudinal slot 223contacts the tab 284 to advance the knife bar 280 and fire the staplecartridge positioned within the channel 302. The spine 210 has anelongated opening or window 213 therein to facilitate assembly andinsertion of the intermediate firing shaft 222 into the spine 210. Oncethe intermediate firing shaft 222 has been inserted therein, a top framesegment 215 may be engaged with the shaft frame 212 to enclose theintermediate firing shaft 222 and knife bar 280 therein. Operation ofthe firing member 220 may be found in U.S. Patent ApplicationPublication No. 2014/0263541. A spine 210 can be configured to slidablysupport a firing member 220 and the closure tube 260 that extends aroundthe spine 210. The spine 210 may slidably support an articulation driver230.

The interchangeable shaft assembly 200 can include a clutch assembly 400configured to selectively and releasably couple the articulation driver230 to the firing member 220. The clutch assembly 400 includes a lockcollar, or lock sleeve 402, positioned around the firing member 220wherein the lock sleeve 402 can be rotated between an engaged positionin which the lock sleeve 402 couples the articulation driver 230 to thefiring member 220 and a disengaged position in which the articulationdriver 230 is not operably coupled to the firing member 220. When thelock sleeve 402 is in the engaged position, distal movement of thefiring member 220 can move the articulation driver 230 distally and,correspondingly, proximal movement of the firing member 220 can move thearticulation driver 230 proximally. When the lock sleeve 402 is in thedisengaged position, movement of the firing member 220 is nottransmitted to the articulation driver 230 and, as a result, the firingmember 220 can move independently of the articulation driver 230. Thenozzle 201 may be employed to operably engage and disengage thearticulation drive system with the firing drive system in the variousmanners described in U.S. Patent Application Publication No.2014/0263541.

The interchangeable shaft assembly 200 can comprise a slip ring assembly600 which can be configured to conduct electrical power to and/or fromthe end effector 300 and/or communicate signals to and/or from the endeffector 300, for example. The slip ring assembly 600 can comprise aproximal connector flange 604 and a distal connector flange 601positioned within a slot defined in the nozzle portions 202, 203. Theproximal connector flange 604 can comprise a first face and the distalconnector flange 601 can comprise a second face positioned adjacent toand movable relative to the first face. The distal connector flange 601can rotate relative to the proximal connector flange 604 about the shaftaxis SA-SA (FIG. 1). The proximal connector flange 604 can comprise aplurality of concentric, or at least substantially concentric,conductors 602 defined in the first face thereof. A connector 607 can bemounted on the proximal side of the distal connector flange 601 and mayhave a plurality of contacts wherein each contact corresponds to and isin electrical contact with one of the conductors 602. Such anarrangement permits relative rotation between the proximal connectorflange 604 and the distal connector flange 601 while maintainingelectrical contact there between. The proximal connector flange 604 caninclude an electrical connector 606 that can place the conductors 602 insignal communication with a shaft circuit board, for example. In atleast one instance, a wiring harness comprising a plurality ofconductors can extend between the electrical connector 606 and the shaftcircuit board. The electrical connector 606 may extend proximallythrough a connector opening defined in the chassis mounting flange. U.S.Patent Application Publication No. 2014/0263551, entitled STAPLECARTRIDGE TISSUE THICKNESS SENSOR SYSTEM, is incorporated herein byreference in its entirety. U.S. Patent Application Publication No.2014/0263552, entitled STAPLE CARTRIDGE TISSUE THICKNESS SENSOR SYSTEM,is incorporated by reference in its entirety. Further details regardingslip ring assembly 600 may be found in U.S. Patent ApplicationPublication No. 2014/0263541.

The interchangeable shaft assembly 200 can include a proximal portionfixably mounted to the handle assembly 14 and a distal portion that isrotatable about a longitudinal axis. The rotatable distal shaft portioncan be rotated relative to the proximal portion about the slip ringassembly 600. The distal connector flange 601 of the slip ring assembly600 can be positioned within the rotatable distal shaft portion.

FIG. 4 is an exploded view of one aspect of an end effector 300 of thesurgical instrument 10 of FIG. 1 according to one aspect of thisdisclosure. The end effector 300 may include the anvil 306 and thesurgical staple cartridge 304. The anvil 306 may be coupled to anelongated channel 302. Apertures 199 can be defined in the elongatedchannel 302 to receive pins 152 extending from the anvil 306 to allowthe anvil 306 to pivot from an open position to a closed positionrelative to the elongated channel 302 and surgical staple cartridge 304.A firing bar 172 is configured to longitudinally translate into the endeffector 300. The firing bar 172 may be constructed from one solidsection, or may include a laminate material comprising a stack of steelplates. The firing bar 172 comprises an I-beam 178 and a cutting edge182 at a distal end thereof. A distally projecting end of the firing bar172 can be attached to the I-beam 178 to assist in spacing the anvil 306from a surgical staple cartridge 304 positioned in the elongated channel302 when the anvil 306 is in a closed position. The I-beam 178 mayinclude a sharpened cutting edge 182 to sever tissue as the I-beam 178is advanced distally by the firing bar 172. In operation, the I-beam 178may, or fire, the surgical staple cartridge 304. The surgical staplecartridge 304 can include a molded cartridge body 194 that holds aplurality of staples 191 resting upon staple drivers 192 withinrespective upwardly open staple cavities 195. A wedge sled 190 is drivendistally by the I-beam 178, sliding upon a cartridge tray 196 of thesurgical staple cartridge 304. The wedge sled 190 upwardly cams thestaple drivers 192 to force out the staples 191 into deforming contactwith the anvil 306 while the cutting edge 182 of the I-beam 178 seversclamped tissue.

The I-beam 178 can include upper pins 180 that engage the anvil 306during firing. The I-beam 178 may include middle pins 184 and a bottomfoot 186 to engage portions of the cartridge body 194, cartridge tray196, and elongated channel 302. When a surgical staple cartridge 304 ispositioned within the elongated channel 302, a slot 193 defined in thecartridge body 194 can be aligned with a longitudinal slot 197 definedin the cartridge tray 196 and a slot 189 defined in the elongatedchannel 302. In use, the I-beam 178 can slide through the alignedlongitudinal slots 193, 197, and 189 wherein, as indicated in FIG. 4,the bottom foot 186 of the I-beam 178 can engage a groove running alongthe bottom surface of elongated channel 302 along the length of slot189, the middle pins 184 can engage the top surfaces of cartridge tray196 along the length of longitudinal slot 197, and the upper pins 180can engage the anvil 306. The I-beam 178 can space, or limit therelative movement between, the anvil 306 and the surgical staplecartridge 304 as the firing bar 172 is advanced distally to fire thestaples from the surgical staple cartridge 304 and/or incise the tissuecaptured between the anvil 306 and the surgical staple cartridge 304.The firing bar 172 and the I-beam 178 can be retracted proximallyallowing the anvil 306 to be opened to release the two stapled andsevered tissue portions.

FIGS. 5A-5B is a block diagram of a control circuit 700 of the surgicalinstrument 10 of FIG. 1 spanning two drawing sheets according to oneaspect of this disclosure. Referring primarily to FIGS. 5A-5B, a handleassembly 702 may include a motor 714 which can be controlled by a motordriver 715 and can be employed by the firing system of the surgicalinstrument 10. In various forms, the motor 714 may be a DC brusheddriving motor having a maximum rotational speed of approximately 25,000RPM. In other arrangements, the motor 714 may include a brushless motor,a cordless motor, a synchronous motor, a stepper motor, or any othersuitable electric motor. The motor driver 715 may comprise an H-Bridgedriver comprising field-effect transistors (FETs) 719, for example. Themotor 714 can be powered by the power assembly 706 releasably mounted tothe handle assembly 200 for supplying control power to the surgicalinstrument 10. The power assembly 706 may comprise a battery which mayinclude a number of battery cells connected in series that can be usedas the power source to power the surgical instrument 10. In certaincircumstances, the battery cells of the power assembly 706 may bereplaceable and/or rechargeable. In at least one example, the batterycells can be Lithium-Ion batteries which can be separably couplable tothe power assembly 706.

The shaft assembly 704 may include a shaft assembly controller 722 whichcan communicate with a safety controller and power management controller716 through an interface while the shaft assembly 704 and the powerassembly 706 are coupled to the handle assembly 702. For example, theinterface may comprise a first interface portion 725 which may includeone or more electric connectors for coupling engagement withcorresponding shaft assembly electric connectors and a second interfaceportion 727 which may include one or more electric connectors forcoupling engagement with corresponding power assembly electricconnectors to permit electrical communication between the shaft assemblycontroller 722 and the power management controller 716 while the shaftassembly 704 and the power assembly 706 are coupled to the handleassembly 702. One or more communication signals can be transmittedthrough the interface to communicate one or more of the powerrequirements of the attached interchangeable shaft assembly 704 to thepower management controller 716. In response, the power managementcontroller may modulate the power output of the battery of the powerassembly 706, as described below in greater detail, in accordance withthe power requirements of the attached shaft assembly 704. Theconnectors may comprise switches which can be activated after mechanicalcoupling engagement of the handle assembly 702 to the shaft assembly 704and/or to the power assembly 706 to allow electrical communicationbetween the shaft assembly controller 722 and the power managementcontroller 716.

The interface can facilitate transmission of the one or morecommunication signals between the power management controller 716 andthe shaft assembly controller 722 by routing such communication signalsthrough a main controller 717 residing in the handle assembly 702, forexample. In other circumstances, the interface can facilitate a directline of communication between the power management controller 716 andthe shaft assembly controller 722 through the handle assembly 702 whilethe shaft assembly 704 and the power assembly 706 are coupled to thehandle assembly 702.

The main controller 717 may be any single core or multicore processorsuch as those known under the trade name ARM Cortex by TexasInstruments. In one aspect, the main controller 717 may be anLM4F230H5QR ARM Cortex-M4F Processor Core, available from TexasInstruments, for example, comprising on-chip memory of 256 KBsingle-cycle flash memory, or other non-volatile memory, up to 40 MHz, aprefetch buffer to improve performance above 40 MHz, a 32 KBsingle-cycle serial random access memory (SRAM), internal read-onlymemory (ROM) loaded with StellarisWare® software, 2 KB electricallyerasable programmable read-only memory (EEPROM), one or more pulse widthmodulation (PWM) modules, one or more quadrature encoder inputs (QEI)analog, one or more 12-bit Analog-to-Digital Converters (ADC) with 12analog input channels, details of which are available for the productdatasheet.

The safety controller may be a safety controller platform comprising twocontroller-based families such as TMS570 and RM4x known under the tradename Hercules ARM Cortex R4, also by Texas Instruments. The safetycontroller may be configured specifically for IEC 61508 and ISO 26262safety critical applications, among others, to provide advancedintegrated safety features while delivering scalable performance,connectivity, and memory options.

The power assembly 706 may include a power management circuit which maycomprise the power management controller 716, a power modulator 738, anda current sense circuit 736. The power management circuit can beconfigured to modulate power output of the battery based on the powerrequirements of the shaft assembly 704 while the shaft assembly 704 andthe power assembly 706 are coupled to the handle assembly 702. The powermanagement controller 716 can be programmed to control the powermodulator 738 of the power output of the power assembly 706 and thecurrent sense circuit 736 can be employed to monitor power output of thepower assembly 706 to provide feedback to the power managementcontroller 716 about the power output of the battery so that the powermanagement controller 716 may adjust the power output of the powerassembly 706 to maintain a desired output. The power managementcontroller 716 and/or the shaft assembly controller 722 each maycomprise one or more processors and/or memory units which may store anumber of software modules.

The surgical instrument 10 (FIGS. 1-4) may comprise an output device 742which may include devices for providing a sensory feedback to a user.Such devices may comprise, for example, visual feedback devices (e.g.,an LCD display screen, LED indicators), audio feedback devices (e.g., aspeaker, a buzzer) or tactile feedback devices (e.g., haptic actuators).In certain circumstances, the output device 742 may comprise a display743 which may be included in the handle assembly 702. The shaft assemblycontroller 722 and/or the power management controller 716 can providefeedback to a user of the surgical instrument 10 through the outputdevice 742. The interface can be configured to connect the shaftassembly controller 722 and/or the power management controller 716 tothe output device 742. The output device 742 can instead be integratedwith the power assembly 706. In such circumstances, communicationbetween the output device 742 and the shaft assembly controller 722 maybe accomplished through the interface while the shaft assembly 704 iscoupled to the handle assembly 702.

The control circuit 700 comprises circuit segments configured to controloperations of the powered surgical instrument 10. A safety controllersegment (Segment 1) comprises a safety controller and the maincontroller 717 segment (Segment 2). The safety controller and/or themain controller 717 are configured to interact with one or moreadditional circuit segments such as an acceleration segment, a displaysegment, a shaft segment, an encoder segment, a motor segment, and apower segment. Each of the circuit segments may be coupled to the safetycontroller and/or the main controller 717. The main controller 717 isalso coupled to a flash memory. The main controller 717 also comprises aserial communication interface. The main controller 717 comprises aplurality of inputs coupled to, for example, one or more circuitsegments, a battery, and/or a plurality of switches. The segmentedcircuit may be implemented by any suitable circuit, such as, forexample, a printed circuit board assembly (PCBA) within the poweredsurgical instrument 10. It should be understood that the term processoras used herein includes any microprocessor, processors, controller,controllers, or other basic computing device that incorporates thefunctions of a computer's central processing unit (CPU) on an integratedcircuit or at most a few integrated circuits. The main controller 717 isa multipurpose, programmable device that accepts digital data as input,processes it according to instructions stored in its memory, andprovides results as output. It is an example of sequential digitallogic, as it has internal memory. The control circuit 700 can beconfigured to implement one or more of the processes described herein.

The acceleration segment (Segment 3) comprises an accelerometer. Theaccelerometer is configured to detect movement or acceleration of thepowered surgical instrument 10. Input from the accelerometer may be usedto transition to and from a sleep mode, identify an orientation of thepowered surgical instrument, and/or identify when the surgicalinstrument has been dropped. In some examples, the acceleration segmentis coupled to the safety controller and/or the main controller 717.

The display segment (Segment 4) comprises a display connector coupled tothe main controller 717. The display connector couples the maincontroller 717 to a display through one or more integrated circuitdrivers of the display. The integrated circuit drivers of the displaymay be integrated with the display and/or may be located separately fromthe display. The display may comprise any suitable display, such as, forexample, an organic light-emitting diode (OLED) display, aliquid-crystal display (LCD), and/or any other suitable display. In someexamples, the display segment is coupled to the safety controller.

The shaft segment (Segment 5) comprises controls for an interchangeableshaft assembly 200 (FIGS. 1 and 3) coupled to the surgical instrument 10(FIGS. 1-4) and/or one or more controls for an end effector 300 coupledto the interchangeable shaft assembly 200. The shaft segment comprises ashaft connector configured to couple the main controller 717 to a shaftPCBA. The shaft PCBA comprises a low-power microcontroller with aferroelectric random access memory (FRAM), an articulation switch, ashaft release Hall effect switch, and a shaft PCBA EEPROM. The shaftPCBA EEPROM comprises one or more parameters, routines, and/or programsspecific to the interchangeable shaft assembly 200 and/or the shaftPCBA. The shaft PCBA may be coupled to the interchangeable shaftassembly 200 and/or integral with the surgical instrument 10. In someexamples, the shaft segment comprises a second shaft EEPROM. The secondshaft EEPROM comprises a plurality of algorithms, routines, parameters,and/or other data corresponding to one or more shaft assemblies 200and/or end effectors 300 that may be interfaced with the poweredsurgical instrument 10.

The position encoder segment (Segment 6) comprises one or more magneticangle rotary position encoders. The one or more magnetic angle rotaryposition encoders are configured to identify the rotational position ofthe motor 714, an interchangeable shaft assembly 200 (FIGS. 1 and 3),and/or an end effector 300 of the surgical instrument 10 (FIGS. 1-4). Insome examples, the magnetic angle rotary position encoders may becoupled to the safety controller and/or the main controller 717.

The motor circuit segment (Segment 7) comprises a motor 714 configuredto control movements of the powered surgical instrument 10 (FIGS. 1-4).The motor 714 is coupled to the main microcontroller processor 717 by anH-bridge driver comprising one or more H-bridge field-effect transistors(FETs) and a motor controller. The H-bridge driver is also coupled tothe safety controller. A motor current sensor is coupled in series withthe motor to measure the current draw of the motor. The motor currentsensor is in signal communication with the main controller 717 and/orthe safety controller. In some examples, the motor 714 is coupled to amotor electromagnetic interference (EMI) filter.

The motor controller controls a first motor flag and a second motor flagto indicate the status and position of the motor 714 to the maincontroller 717. The main controller 717 provides a pulse-widthmodulation (PWM) high signal, a PWM low signal, a direction signal, asynchronize signal, and a motor reset signal to the motor controllerthrough a buffer. The power segment is configured to provide a segmentvoltage to each of the circuit segments.

The power segment (Segment 8) comprises a battery coupled to the safetycontroller, the main controller 717, and additional circuit segments.The battery is coupled to the segmented circuit by a battery connectorand a current sensor. The current sensor is configured to measure thetotal current draw of the segmented circuit. In some examples, one ormore voltage converters are configured to provide predetermined voltagevalues to one or more circuit segments. For example, in some examples,the segmented circuit may comprise 3.3V voltage converters and/or 5Vvoltage converters. A boost converter is configured to provide a boostvoltage up to a predetermined amount, such as, for example, up to 13V.The boost converter is configured to provide additional voltage and/orcurrent during power intensive operations and prevent brownout orlow-power conditions.

A plurality of switches are coupled to the safety controller and/or themain controller 717. The switches may be configured to controloperations of the surgical instrument 10 (FIGS. 1-4), of the segmentedcircuit, and/or indicate a status of the surgical instrument 10. Abail-out door switch and Hall effect switch for bailout are configuredto indicate the status of a bail-out door. A plurality of articulationswitches, such as, for example, a left side articulation left switch, aleft side articulation right switch, a left side articulation centerswitch, a right side articulation left switch, a right side articulationright switch, and a right side articulation center switch are configuredto control articulation of an interchangeable shaft assembly 200 (FIGS.1 and 3) and/or the end effector 300 (FIGS. 1 and 4). A left sidereverse switch and a right side reverse switch are coupled to the maincontroller 717. The left side switches comprising the left sidearticulation left switch, the left side articulation right switch, theleft side articulation center switch, and the left side reverse switchare coupled to the main controller 717 by a left flex connector. Theright side switches comprising the right side articulation left switch,the right side articulation right switch, the right side articulationcenter switch, and the right side reverse switch are coupled to the maincontroller 717 by a right flex connector. A firing switch, a clamprelease switch, and a shaft engaged switch are coupled to the maincontroller 717.

Any suitable mechanical, electromechanical, or solid state switches maybe employed to implement the plurality of switches, in any combination.For example, the switches may be limit switches operated by the motionof components associated with the surgical instrument 10 (FIGS. 1-4) orthe presence of an object. Such switches may be employed to controlvarious functions associated with the surgical instrument 10. A limitswitch is an electromechanical device that consists of an actuatormechanically linked to a set of contacts. When an object comes intocontact with the actuator, the device operates the contacts to make orbreak an electrical connection. Limit switches are used in a variety ofapplications and environments because of their ruggedness, ease ofinstallation, and reliability of operation. They can determine thepresence or absence, passing, positioning, and end of travel of anobject. In other implementations, the switches may be solid stateswitches that operate under the influence of a magnetic field such asHall-effect devices, magneto-resistive (MR) devices, giantmagneto-resistive (GMR) devices, magnetometers, among others. In otherimplementations, the switches may be solid state switches that operateunder the influence of light, such as optical sensors, infrared sensors,ultraviolet sensors, among others. Still, the switches may be solidstate devices such as transistors (e.g., FET, Junction-FET, metal-oxidesemiconductor-FET (MOSFET), bipolar, and the like). Other switches mayinclude wireless switches, ultrasonic switches, accelerometers, inertialsensors, among others.

FIG. 6 is another block diagram of the control circuit 700 of thesurgical instrument of FIG. 1 illustrating interfaces between the handleassembly 702 and the power assembly 706 and between the handle assembly702 and the interchangeable shaft assembly 704 according to one aspectof this disclosure. The handle assembly 702 may comprise a maincontroller 717, a shaft assembly connector 726 and a power assemblyconnector 730. The power assembly 706 may include a power assemblyconnector 732, a power management circuit 734 that may comprise thepower management controller 716, a power modulator 738, and a currentsense circuit 736. The shaft assembly connectors 730, 732 form aninterface 727. The power management circuit 734 can be configured tomodulate power output of the battery 707 based on the power requirementsof the interchangeable shaft assembly 704 while the interchangeableshaft assembly 704 and the power assembly 706 are coupled to the handleassembly 702. The power management controller 716 can be programmed tocontrol the power modulator 738 of the power output of the powerassembly 706 and the current sense circuit 736 can be employed tomonitor power output of the power assembly 706 to provide feedback tothe power management controller 716 about the power output of thebattery 707 so that the power management controller 716 may adjust thepower output of the power assembly 706 to maintain a desired output. Theshaft assembly 704 comprises a shaft processor 719 coupled to anon-volatile memory 721 and shaft assembly connector 728 to electricallycouple the shaft assembly 704 to the handle assembly 702. The shaftassembly connectors 726, 728 form interface 725. The main controller717, the shaft processor 719, and/or the power management controller 716can be configured to implement one or more of the processes describedherein.

The surgical instrument 10 (FIGS. 1-4) may comprise an output device 742to a sensory feedback to a user. Such devices may comprise visualfeedback devices (e.g., an LCD display screen, LED indicators), audiofeedback devices (e.g., a speaker, a buzzer), or tactile feedbackdevices (e.g., haptic actuators). In certain circumstances, the outputdevice 742 may comprise a display 743 that may be included in the handleassembly 702. The shaft assembly controller 722 and/or the powermanagement controller 716 can provide feedback to a user of the surgicalinstrument 10 through the output device 742. The interface 727 can beconfigured to connect the shaft assembly controller 722 and/or the powermanagement controller 716 to the output device 742. The output device742 can be integrated with the power assembly 706. Communication betweenthe output device 742 and the shaft assembly controller 722 may beaccomplished through the interface 725 while the interchangeable shaftassembly 704 is coupled to the handle assembly 702. Having described acontrol circuit 700 (FIGS. 5A-5B and 6) for controlling the operation ofthe surgical instrument 10 (FIGS. 1-4), the disclosure now turns tovarious configurations of the surgical instrument 10 (FIGS. 1-4) andcontrol circuit 700.

FIG. 7 illustrates a control circuit 800 configured to control aspectsof the surgical instrument 10 (FIGS. 1-4) according to one aspect ofthis disclosure. The control circuit 800 can be configured to implementvarious processes described herein. The control circuit 800 may comprisea controller comprising one or more processors 802 (e.g.,microprocessor, microcontroller) coupled to at least one memory circuit804. The memory circuit 804 stores machine executable instructions thatwhen executed by the processor 802, cause the processor 802 to executemachine instructions to implement various processes described herein.The processor 802 may be any one of a number of single or multi-coreprocessors known in the art. The memory circuit 804 may comprisevolatile and non-volatile storage media. The processor 802 may includean instruction processing unit 806 and an arithmetic unit 808. Theinstruction processing unit may be configured to receive instructionsfrom the memory circuit 804.

FIG. 8 illustrates a combinational logic circuit 810 configured tocontrol aspects of the surgical instrument 10 (FIGS. 1-4) according toone aspect of this disclosure. The combinational logic circuit 810 canbe configured to implement various processes described herein. Thecircuit 810 may comprise a finite state machine comprising acombinational logic circuit 812 configured to receive data associatedwith the surgical instrument 10 at an input 814, process the data by thecombinational logic 812, and provide an output 816.

FIG. 9 illustrates a sequential logic circuit 820 configured to controlaspects of the surgical instrument 10 (FIGS. 1-4) according to oneaspect of this disclosure. The sequential logic circuit 820 or thecombinational logic circuit 822 can be configured to implement variousprocesses described herein. The circuit 820 may comprise a finite statemachine. The sequential logic circuit 820 may comprise a combinationallogic circuit 822, at least one memory circuit 824, and a clock 829, forexample. The at least one memory circuit 820 can store a current stateof the finite state machine. In certain instances, the sequential logiccircuit 820 may be synchronous or asynchronous. The combinational logiccircuit 822 is configured to receive data associated with the surgicalinstrument 10 an input 826, process the data by the combinational logiccircuit 822, and provide an output 828. In other aspects, the circuitmay comprise a combination of the processor 802 and the finite statemachine to implement various processes herein. In other aspects, thefinite state machine may comprise a combination of the combinationallogic circuit 810 and the sequential logic circuit 820.

Aspects may be implemented as an article of manufacture. The article ofmanufacture may include a computer readable storage medium arranged tostore logic, instructions, and/or data for performing various operationsof one or more aspects. For example, the article of manufacture maycomprise a magnetic disk, optical disk, flash memory, or firmwarecontaining computer program instructions suitable for execution by ageneral purpose processor or application specific processor.

FIG. 10 is a diagram of an absolute positioning system 1100 of thesurgical instrument 10 (FIGS. 1-4) where the absolute positioning system1100 comprises a controlled motor drive circuit arrangement comprising asensor arrangement 1102 according to one aspect of this disclosure. Thesensor arrangement 1102 for an absolute positioning system 1100 providesa unique position signal corresponding to the location of a displacementmember 1111. Turning briefly to FIGS. 2-4, in one aspect thedisplacement member 1111 represents the longitudinally movable drivemember 120 (FIG. 2) comprising a rack of drive teeth 122 for meshingengagement with a corresponding drive gear 86 of the gear reducerassembly 84. In other aspects, the displacement member 1111 representsthe firing member 220 (FIG. 3), which could be adapted and configured toinclude a rack of drive teeth. In yet another aspect, the displacementmember 1111 represents the firing bar 172 (FIG. 4) or the I-beam 178(FIG. 4), each of which can be adapted and configured to include a rackof drive teeth. Accordingly, as used herein, the term displacementmember is used generically to refer to any movable member of thesurgical instrument 10 such as the drive member 120, the firing member220, the firing bar 172, the I-beam 178, or any element that can bedisplaced. In one aspect, the longitudinally movable drive member 120 iscoupled to the firing member 220, the firing bar 172, and the I-beam178. Accordingly, the absolute positioning system 1100 can, in effect,track the linear displacement of the I-beam 178 by tracking the lineardisplacement of the longitudinally movable drive member 120. In variousother aspects, the displacement member 1111 may be coupled to any sensorsuitable for measuring linear displacement. Thus, the longitudinallymovable drive member 120, the firing member 220, the firing bar 172, orthe I-beam 178, or combinations, may be coupled to any suitable lineardisplacement sensor. Linear displacement sensors may include contact ornon-contact displacement sensors. Linear displacement sensors maycomprise linear variable differential transformers (LVDT), differentialvariable reluctance transducers (DVRT), a slide potentiometer, amagnetic sensing system comprising a movable magnet and a series oflinearly arranged Hall effect sensors, a magnetic sensing systemcomprising a fixed magnet and a series of movable linearly arranged Halleffect sensors, an optical sensing system comprising a movable lightsource and a series of linearly arranged photo diodes or photodetectors, or an optical sensing system comprising a fixed light sourceand a series of movable linearly arranged photo diodes or photodetectors, or any combination thereof.

An electric motor 1120 can include a rotatable shaft 1116 that operablyinterfaces with a gear assembly 1114 that is mounted in meshingengagement with a set, or rack, of drive teeth on the displacementmember 1111. A sensor element 1126 may be operably coupled to a gearassembly 1114 such that a single revolution of the sensor element 1126corresponds to some linear longitudinal translation of the displacementmember 1111. An arrangement of gearing and sensors 1118 can be connectedto the linear actuator via a rack and pinion arrangement or a rotaryactuator via a spur gear or other connection. A power source 1129supplies power to the absolute positioning system 1100 and an outputindicator 1128 may display the output of the absolute positioning system1100. In FIG. 2, the displacement member 1111 represents thelongitudinally movable drive member 120 comprising a rack of drive teeth122 formed thereon for meshing engagement with a corresponding drivegear 86 of the gear reducer assembly 84. The displacement member 1111represents the longitudinally movable firing member 220, firing bar 172,I-beam 178, or combinations thereof.

A single revolution of the sensor element 1126 associated with theposition sensor 1112 is equivalent to a longitudinal linear displacementd1 of the of the displacement member 1111, where d1 is the longitudinallinear distance that the displacement member 1111 moves from point “a”to point “b” after a single revolution of the sensor element 1126coupled to the displacement member 1111. The sensor arrangement 1102 maybe connected via a gear reduction that results in the position sensor1112 completing one or more revolutions for the full stroke of thedisplacement member 1111. The position sensor 1112 may complete multiplerevolutions for the full stroke of the displacement member 1111.

A series of switches 1122 a-1122 n, where n is an integer greater thanone, may be employed alone or in combination with gear reduction toprovide a unique position signal for more than one revolution of theposition sensor 1112. The state of the switches 1122 a-1122 n are fedback to a controller 1104 that applies logic to determine a uniqueposition signal corresponding to the longitudinal linear displacementd1+d2+ . . . do of the displacement member 1111. The output 1124 of theposition sensor 1112 is provided to the controller 1104. The positionsensor 1112 of the sensor arrangement 1102 may comprise a magneticsensor, an analog rotary sensor like a potentiometer, an array of analogHall-effect elements, which output a unique combination of positionsignals or values.

The absolute positioning system 1100 provides an absolute position ofthe displacement member 1111 upon power up of the instrument withoutretracting or advancing the displacement member 1111 to a reset (zero orhome) position as may be required with conventional rotary encoders thatmerely count the number of steps forwards or backwards that the motor1120 has taken to infer the position of a device actuator, drive bar,knife, and the like.

The controller 1104 may be programmed to perform various functions suchas precise control over the speed and position of the knife andarticulation systems. In one aspect, the controller 1104 includes aprocessor 1108 and a memory 1106. The electric motor 1120 may be abrushed DC motor with a gearbox and mechanical links to an articulationor knife system. In one aspect, a motor driver 1110 may be an A3941available from Allegro Microsystems, Inc. Other motor drivers may bereadily substituted for use in the absolute positioning system 1100. Amore detailed description of the absolute positioning system 1100 isdescribed in U.S. patent application Ser. No. 15/130,590, entitledSYSTEMS AND METHODS FOR CONTROLLING A SURGICAL STAPLING AND CUTTINGINSTRUMENT, filed on Apr. 15, 2016, the entire disclosure of which isherein incorporated by reference.

The controller 1104 may be programmed to provide precise control overthe speed and position of the displacement member 1111 and articulationsystems. The controller 1104 may be configured to compute a response inthe software of the controller 1104. The computed response is comparedto a measured response of the actual system to obtain an “observed”response, which is used for actual feedback decisions. The observedresponse is a favorable, tuned, value that balances the smooth,continuous nature of the simulated response with the measured response,which can detect outside influences on the system.

The absolute positioning system 1100 may comprise and/or be programmedto implement a feedback controller, such as a PID, state feedback, andadaptive controller. A power source 1129 converts the signal from thefeedback controller into a physical input to the system, in this casevoltage. Other examples include pulse width modulation (PWM) of thevoltage, current, and force. Other sensor(s) 1118 may be provided tomeasure physical parameters of the physical system in addition toposition measured by the position sensor 1112. In a digital signalprocessing system, absolute positioning system 1100 is coupled to adigital data acquisition system where the output of the absolutepositioning system 1100 will have finite resolution and samplingfrequency. The absolute positioning system 1100 may comprise a compareand combine circuit to combine a computed response with a measuredresponse using algorithms such as weighted average and theoreticalcontrol loop that drives the computed response towards the measuredresponse. The computed response of the physical system takes intoaccount properties like mass, inertial, viscous friction, inductanceresistance, etc., to predict what the states and outputs of the physicalsystem will be by knowing the input. The controller 1104 may be acontrol circuit 700 (FIGS. 5A-5B).

The motor driver 1110 may be an A3941 available from AllegroMicrosystems, Inc. The A3941 driver 1110 is a full-bridge controller foruse with external N-channel power metal oxide semiconductor field effecttransistors (MOSFETs) specifically designed for inductive loads, such asbrush DC motors. The driver 1110 comprises a unique charge pumpregulator provides full (>10 V) gate drive for battery voltages down to7 V and allows the A3941 to operate with a reduced gate drive, down to5.5 V. A bootstrap capacitor may be employed to provide theabove-battery supply voltage required for N-channel MOSFETs. An internalcharge pump for the high-side drive allows DC (100% duty cycle)operation. The full bridge can be driven in fast or slow decay modesusing diode or synchronous rectification. In the slow decay mode,current recirculation can be through the high-side or the lowside FETs.The power FETs are protected from shoot-through by resistor adjustabledead time. Integrated diagnostics provide indication of undervoltage,overtemperature, and power bridge faults, and can be configured toprotect the power MOSFETs under most short circuit conditions. Othermotor drivers may be readily substituted for use in the absolutepositioning system 1100.

Having described a general architecture for implementing aspects of anabsolute positioning system 1100 for a sensor arrangement 1102, thedisclosure now turns to FIGS. 11 and 12 for a description of one aspectof a sensor arrangement 1102 for the absolute positioning system 1100.FIG. 11 is an exploded perspective view of the sensor arrangement 1102for the absolute positioning system 1100 showing a circuit 1205 and therelative alignment of the elements of the sensor arrangement 1102,according to one aspect. The sensor arrangement 1102 for an absolutepositioning system 1100 comprises a position sensor 1200, a magnet 1202sensor element, a magnet holder 1204 that turns once every full strokeof the displacement member 1111, and a gear assembly 1206 to provide agear reduction. With reference briefly to FIG. 2, the displacementmember 1111 may represent the longitudinally movable drive member 120comprising a rack of drive teeth 122 for meshing engagement with acorresponding drive gear 86 of the gear reducer assembly 84. Returningto FIG. 11, a structural element such as bracket 1216 is provided tosupport the gear assembly 1206, the magnet holder 1204, and the magnet1202. The position sensor 1200 comprises magnetic sensing elements suchas Hall elements and is placed in proximity to the magnet 1202. As themagnet 1202 rotates, the magnetic sensing elements of the positionsensor 1200 determine the absolute angular position of the magnet 1202over one revolution.

The sensor arrangement 1102 may comprises any number of magnetic sensingelements, such as, for example, magnetic sensors classified according towhether they measure the total magnetic field or the vector componentsof the magnetic field. The techniques used to produce both types ofmagnetic sensors encompass many aspects of physics and electronics. Thetechnologies used for magnetic field sensing include search coil,fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect,anisotropic magnetoresistance, giant magnetoresistance, magnetic tunneljunctions, giant magnetoimpedance, magnetostrictive/piezoelectriccomposites, magnetodiode, magnetotransistor, fiber optic, magnetooptic,and microelectromechanical systems-based magnetic sensors, among others.

A gear assembly comprises a first gear 1208 and a second gear 1210 inmeshing engagement to provide a 3:1 gear ratio connection. A third gear1212 rotates about a shaft 1214. The third gear 1212 is in meshingengagement with the displacement member 1111 (or 120 as shown in FIG. 2)and rotates in a first direction as the displacement member 1111advances in a distal direction D and rotates in a second direction asthe displacement member 1111 retracts in a proximal direction P. Thesecond gear 1210 also rotates about the shaft 1214 and, therefore,rotation of the second gear 1210 about the shaft 1214 corresponds to thelongitudinal translation of the displacement member 1111. Thus, one fullstroke of the displacement member 1111 in either the distal or proximaldirections D, P corresponds to three rotations of the second gear 1210and a single rotation of the first gear 1208. Since the magnet holder1204 is coupled to the first gear 1208, the magnet holder 1204 makes onefull rotation with each full stroke of the displacement member 1111.

The position sensor 1200 is supported by a position sensor holder 1218defining an aperture 1220 suitable to contain the position sensor 1200in precise alignment with a magnet 1202 rotating below within the magnetholder 1204. The fixture is coupled to the bracket 1216 and to thecircuit 1205 and remains stationary while the magnet 1202 rotates withthe magnet holder 1204. A hub 1222 is provided to mate with the firstgear 1208 and the magnet holder 1204. The second gear 1210 and thirdgear 1212 coupled to shaft 1214 also are shown.

FIG. 12 is a diagram of a position sensor 1200 for an absolutepositioning system 1100 comprising a magnetic rotary absolutepositioning system according to one aspect of this disclosure. Theposition sensor 1200 may be implemented as an AS5055EQFT single-chipmagnetic rotary position sensor available from Austria Microsystems, AG.The position sensor 1200 is interfaced with the controller 1104 toprovide an absolute positioning system 1100. The position sensor 1200 isa low-voltage and low-power component and includes four Hall-effectelements 1228A, 1228B, 1228C, 1228D in an area 1230 of the positionsensor 1200 that is located above the magnet 1202 (FIGS. 15 and 16). Ahigh-resolution ADC 1232 and a smart power management controller 1238are also provided on the chip. A CORDIC processor 1236 (for CoordinateRotation Digital Computer), also known as the digit-by-digit method andVolder's algorithm, is provided to implement a simple and efficientalgorithm to calculate hyperbolic and trigonometric functions thatrequire only addition, subtraction, bitshift, and table lookupoperations. The angle position, alarm bits, and magnetic fieldinformation are transmitted over a standard serial communicationinterface such as an SPI interface 1234 to the controller 1104. Theposition sensor 1200 provides 12 or 14 bits of resolution. The positionsensor 1200 may be an AS5055 chip provided in a small QFN 16-pin4×4×0.85 mm package.

The Hall-effect elements 1228A, 1228B, 1228C, 1228D are located directlyabove the rotating magnet 1202 (FIG. 11). The Hall-effect is awell-known effect and for expediency will not be described in detailherein, however, generally, the Hall-effect produces a voltagedifference (the Hall voltage) across an electrical conductor transverseto an electric current in the conductor and a magnetic fieldperpendicular to the current. A Hall coefficient is defined as the ratioof the induced electric field to the product of the current density andthe applied magnetic field. It is a characteristic of the material fromwhich the conductor is made, since its value depends on the type,number, and properties of the charge carriers that constitute thecurrent. In the AS5055 position sensor 1200, the Hall-effect elements1228A, 1228B, 1228C, 1228D are capable producing a voltage signal thatis indicative of the absolute position of the magnet 1202 in terms ofthe angle over a single revolution of the magnet 1202. This value of theangle, which is unique position signal, is calculated by the CORDICprocessor 1236 is stored onboard the AS5055 position sensor 1200 in aregister or memory. The value of the angle that is indicative of theposition of the magnet 1202 over one revolution is provided to thecontroller 1104 in a variety of techniques, e.g., upon power up or uponrequest by the controller 1104.

The AS5055 position sensor 1200 requires only a few external componentsto operate when connected to the controller 1104. Six wires are neededfor a simple application using a single power supply: two wires forpower and four wires 1240 for the SPI interface 1234 with the controller1104. A seventh connection can be added in order to send an interrupt tothe controller 1104 to inform that a new valid angle can be read. Uponpower-up, the AS5055 position sensor 1200 performs a full power-upsequence including one angle measurement. The completion of this cycleis indicated as an INT output 1242, and the angle value is stored in aninternal register. Once this output is set, the AS5055 position sensor1200 suspends to sleep mode. The controller 1104 can respond to the INTrequest at the INT output 1242 by reading the angle value from theAS5055 position sensor 1200 over the SPI interface 1234. Once the anglevalue is read by the controller 1104, the INT output 1242 is clearedagain. Sending a “read angle” command by the SPI interface 1234 by thecontroller 1104 to the position sensor 1200 also automatically powers upthe chip and starts another angle measurement. As soon as the controller1104 has completed reading of the angle value, the INT output 1242 iscleared and a new result is stored in the angle register. The completionof the angle measurement is again indicated by setting the INT output1242 and a corresponding flag in the status register.

Due to the measurement principle of the AS5055 position sensor 1200,only a single angle measurement is performed in very short time (˜600μs) after each power-up sequence. As soon as the measurement of oneangle is completed, the AS5055 position sensor 1200 suspends topower-down state. An on-chip filtering of the angle value by digitalaveraging is not implemented, as this would require more than one anglemeasurement and, consequently, a longer power-up time that is notdesired in low-power applications. The angle jitter can be reduced byaveraging of several angle samples in the controller 1104. For example,an averaging of four samples reduces the jitter by 6 dB (50%).

FIG. 13 is a section view of an end effector 2502 of the surgicalinstrument 10 (FIGS. 1-4) showing an I-beam 2514 firing stroke relativeto tissue 2526 grasped within the end effector 2502 according to oneaspect of this disclosure. The end effector 2502 is configured tooperate with the surgical instrument 10 shown in FIGS. 1-4. The endeffector 2502 comprises an anvil 2516 and an elongated channel 2503 witha staple cartridge 2518 positioned in the elongated channel 2503. Afiring bar 2520 is translatable distally and proximally along alongitudinal axis 2515 of the end effector 2502. When the end effector2502 is not articulated, the end effector 2502 is in line with the shaftof the instrument. An I-beam 2514 comprising a cutting edge 2509 isillustrated at a distal portion of the firing bar 2520. A wedge sled2513 is positioned in the staple cartridge 2518. As the I-beam 2514translates distally, the cutting edge 2509 contacts and may cut tissue2526 positioned between the anvil 2516 and the staple cartridge 2518.Also, the I-beam 2514 contacts the wedge sled 2513 and pushes itdistally, causing the wedge sled 2513 to contact staple drivers 2511.The staple drivers 2511 may be driven up into staples 2505, causing thestaples 2505 to advance through tissue and into pockets 2507 defined inthe anvil 2516, which shape the staples 2505.

An example I-beam 2514 firing stroke is illustrated by a chart 2529aligned with the end effector 2502. Example tissue 2526 is also shownaligned with the end effector 2502. The firing member stroke maycomprise a stroke begin position 2527 and a stroke end position 2528.During an I-beam 2514 firing stroke, the I-beam 2514 may be advanceddistally from the stroke begin position 2527 to the stroke end position2528. The I-beam 2514 is shown at one example location of a stroke beginposition 2527. The I-beam 2514 firing member stroke chart 2529illustrates five firing member stroke regions 2517, 2519, 2521, 2523,2525. In a first firing stroke region 2517, the I-beam 2514 may begin toadvance distally. In the first firing stroke region 2517, the I-beam2514 may contact the wedge sled 2513 and begin to move it distally.While in the first region, however, the cutting edge 2509 may notcontact tissue and the wedge sled 2513 may not contact a staple driver2511. After static friction is overcome, the force to drive the I-beam2514 in the first region 2517 may be substantially constant.

In the second firing member stroke region 2519, the cutting edge 2509may begin to contact and cut tissue 2526. Also, the wedge sled 2513 maybegin to contact staple drivers 2511 to drive staples 2505. Force todrive the I-beam 2514 may begin to ramp up. As shown, tissue encounteredinitially may be compressed and/or thinner because of the way that theanvil 2516 pivots relative to the staple cartridge 2518. In the thirdfiring member stroke region 2521, the cutting edge 2509 may continuouslycontact and cut tissue 2526 and the wedge sled 2513 may repeatedlycontact staple drivers 2511. Force to drive the I-beam 2514 may plateauin the third region 2521. By the fourth firing stroke region 2523, forceto drive the I-beam 2514 may begin to decline. For example, tissue inthe portion of the end effector 2502 corresponding to the fourth firingregion 2523 may be less compressed than tissue closer to the pivot pointof the anvil 2516, requiring less force to cut. Also, the cutting edge2509 and wedge sled 2513 may reach the end of the tissue 2526 while inthe fourth region 2523. When the I-beam 2514 reaches the fifth region2525, the tissue 2526 may be completely severed. The wedge sled 2513 maycontact one or more staple drivers 2511 at or near the end of thetissue. Force to advance the I-beam 2514 through the fifth region 2525may be reduced and, in some examples, may be similar to the force todrive the I-beam 2514 in the first region 2517. At the conclusion of thefiring member stroke, the I-beam 2514 may reach the stroke end position2528. The positioning of firing member stroke regions 2517, 2519, 2521,2523, 2525 in FIG. 18 is just one example. In some examples, differentregions may begin at different positions along the end effectorlongitudinal axis 2515, for example, based on the positioning of tissuebetween the anvil 2516 and the staple cartridge 2518.

As discussed above and with reference now to FIGS. 10-13, the electricmotor 1122 positioned within the handle assembly of the surgicalinstrument 10 (FIGS. 1-4) can be utilized to advance and/or retract thefiring system of the shaft assembly, including the I-beam 2514, relativeto the end effector 2502 of the shaft assembly in order to staple and/orincise tissue captured within the end effector 2502. The I-beam 2514 maybe advanced or retracted at a desired speed, or within a range ofdesired speeds. The controller 1104 may be configured to control thespeed of the I-beam 2514. The controller 1104 may be configured topredict the speed of the I-beam 2514 based on various parameters of thepower supplied to the electric motor 1122, such as voltage and/orcurrent, for example, and/or other operating parameters of the electricmotor 1122 or external influences. The controller 1104 may be configuredto predict the current speed of the I-beam 2514 based on the previousvalues of the current and/or voltage supplied to the electric motor1122, and/or previous states of the system like velocity, acceleration,and/or position. The controller 1104 may be configured to sense thespeed of the I-beam 2514 utilizing the absolute positioning sensorsystem described herein. The controller can be configured to compare thepredicted speed of the I-beam 2514 and the sensed speed of the I-beam2514 to determine whether the power to the electric motor 1122 should beincreased in order to increase the speed of the I-beam 2514 and/ordecreased in order to decrease the speed of the I-beam 2514. U.S. Pat.No. 8,210,411, entitled MOTOR-DRIVEN SURGICAL CUTTING INSTRUMENT, whichis incorporated herein by reference in its entirety. U.S. Pat. No.7,845,537, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES,which is incorporated herein by reference in its entirety.

Force acting on the I-beam 2514 may be determined using varioustechniques. The I-beam 2514 force may be determined by measuring themotor 2504 current, where the motor 2504 current is based on the loadexperienced by the I-beam 2514 as it advances distally. The I-beam 2514force may be determined by positioning a strain gauge on the drivemember 120 (FIG. 2), the firing member 220 (FIG. 2), I-beam 2514 (I-beam178, FIG. 20), the firing bar 172 (FIG. 2), and/or on a proximal end ofthe cutting edge 2509. The I-beam 2514 force may be determined bymonitoring the actual position of the I-beam 2514 moving at an expectedvelocity based on the current set velocity of the motor 2504 after apredetermined elapsed period T₁ and comparing the actual position of theI-beam 2514 relative to the expected position of the I-beam 2514 basedon the current set velocity of the motor 2504 at the end of the periodT₁. Thus, if the actual position of the I-beam 2514 is less than theexpected position of the I-beam 2514, the force on the I-beam 2514 isgreater than a nominal force. Conversely, if the actual position of theI-beam 2514 is greater than the expected position of the I-beam 2514,the force on the I-beam 2514 is less than the nominal force. Thedifference between the actual and expected positions of the I-beam 2514is proportional to the deviation of the force on the I-beam 2514 fromthe nominal force. Such techniques are described in U.S. patentapplication Ser. No. 15/628,075, entitled SYSTEMS AND METHODS FORCONTROLLING MOTOR VELOCITY OF A SURGICAL STAPLING AND CUTTINGINSTRUMENT, now U.S. Pat. No. 10,624,633, which is incorporated hereinby reference in its entirety.

FIG. 14 illustrates a block diagram of a surgical instrument 2500programmed to control distal translation of a displacement memberaccording to one aspect of this disclosure. In one aspect, the surgicalinstrument 2500 is programmed to control distal translation of adisplacement member 1111 such as the I-beam 2514. The surgicalinstrument 2500 comprises an end effector 2502 that may comprise ananvil 2516, an I-beam 2514 (including a sharp cutting edge 2509), and aremovable staple cartridge 2518. The end effector 2502, anvil 2516,I-beam 2514, and staple cartridge 2518 may be configured as describedherein, for example, with respect to FIGS. 1-13.

The position, movement, displacement, and/or translation of a linerdisplacement member 1111, such as the I-beam 2514, can be measured bythe absolute positioning system 1100, sensor arrangement 1102, andposition sensor 1200 as shown in FIGS. 10-12 and represented as positionsensor 2534 in FIG. 14. Because the I-beam 2514 is coupled to thelongitudinally movable drive member 120, the position of the I-beam 2514can be determined by measuring the position of the longitudinallymovable drive member 120 employing the position sensor 2534.Accordingly, in the following description, the position, displacement,and/or translation of the I-beam 2514 can be achieved by the positionsensor 2534 as described herein. A control circuit 2510, such as thecontrol circuit 700 described in FIGS. 5A and 5B, may be programmed tocontrol the translation of the displacement member 1111, such as theI-beam 2514, as described in connection with FIGS. 10-12. The controlcircuit 2510, in some examples, may comprise one or moremicrocontrollers, microprocessors, or other suitable processors forexecuting instructions that cause the processor or processors to controlthe displacement member, e.g., the I-beam 2514, in the manner described.In one aspect, a timer/counter circuit 2531 provides an output signal,such as elapsed time or a digital count, to the control circuit 2510 tocorrelate the position of the I-beam 2514 as determined by the positionsensor 2534 with the output of the timer/counter circuit 2531 such thatthe control circuit 2510 can determine the position of the I-beam 2514at a specific time (t) relative to a starting position. Thetimer/counter circuit 2531 may be configured to measure elapsed time,count external evens, or time external events.

The control circuit 2510 may generate a motor set point signal 2522. Themotor set point signal 2522 may be provided to a motor controller 2508.The motor controller 2508 may comprise one or more circuits configuredto provide a motor drive signal 2524 to the motor 2504 to drive themotor 2504 as described herein. In some examples, the motor 2504 may bea brushed DC electric motor, such as the motor 82, 714, 1120 shown inFIGS. 1, 5B, 10. For example, the velocity of the motor 2504 may beproportional to the motor drive signal 2524. In some examples, the motor2504 may be a brushless direct current (DC) electric motor and the motordrive signal 2524 may comprise a pulse-width-modulated (PWM) signalprovided to one or more stator windings of the motor 2504. Also, in someexamples, the motor controller 2508 may be omitted and the controlcircuit 2510 may generate the motor drive signal 2524 directly.

The motor 2504 may receive power from an energy source 2512. The energysource 2512 may be or include a battery, a super capacitor, or any othersuitable energy source 2512. The motor 2504 may be mechanically coupledto the I-beam 2514 via a transmission 2506. The transmission 2506 mayinclude one or more gears or other linkage components to couple themotor 2504 to the I-beam 2514. A position sensor 2534 may sense aposition of the I-beam 2514. The position sensor 2534 may be or includeany type of sensor that is capable of generating position data thatindicates a position of the I-beam 2514. In some examples, the positionsensor 2534 may include an encoder configured to provide a series ofpulses to the control circuit 2510 as the I-beam 2514 translatesdistally and proximally. The control circuit 2510 may track the pulsesto determine the position of the I-beam 2514. Other suitable positionsensor may be used, including, for example, a proximity sensor. Othertypes of position sensors may provide other signals indicating motion ofthe I-beam 2514. Also, in some examples, the position sensor 2534 may beomitted. Where the motor 2504 is a stepper motor, the control circuit2510 may track the position of the I-beam 2514 by aggregating the numberand direction of steps that the motor 2504 has been instructed toexecute. The position sensor 2534 may be located in the end effector2502 or at any other portion of the instrument.

The control circuit 2510 may be in communication with one or moresensors 2538. The sensors 2538 may be positioned on the end effector2502 and adapted to operate with the surgical instrument 2500 to measurethe various derived parameters such as gap distance versus time, tissuecompression versus time, and anvil strain versus time. The sensors 2538may comprise a magnetic sensor, a magnetic field sensor, a strain gauge,a pressure sensor, a force sensor, an inductive sensor such as an eddycurrent sensor, a resistive sensor, a capacitive sensor, an opticalsensor, and/or any other suitable sensor for measuring one or moreparameters of the end effector 2502. The sensors 2538 may include one ormore sensors.

The one or more sensors 2538 may comprise a strain gauge, such as amicro-strain gauge, configured to measure the magnitude of the strain inthe anvil 2516 during a clamped condition. The strain gauge provides anelectrical signal whose amplitude varies with the magnitude of thestrain. The sensors 2538 may comprise a pressure sensor configured todetect a pressure generated by the presence of compressed tissue betweenthe anvil 2516 and the staple cartridge 2518. The sensors 2538 may beconfigured to detect impedance of a tissue section located between theanvil 2516 and the staple cartridge 2518 that is indicative of thethickness and/or fullness of tissue located therebetween.

The sensors 2538 may be is configured to measure forces exerted on theanvil 2516 by the closure drive system 30. For example, one or moresensors 2538 can be at an interaction point between the closure tube 260(FIG. 3) and the anvil 2516 to detect the closure forces applied by theclosure tube 260 to the anvil 2516. The forces exerted on the anvil 2516can be representative of the tissue compression experienced by thetissue section captured between the anvil 2516 and the staple cartridge2518. The one or more sensors 2538 can be positioned at variousinteraction points along the closure drive system 30 (FIG. 2) to detectthe closure forces applied to the anvil 2516 by the closure drive system30. The one or more sensors 2538 may be sampled in real time during aclamping operation by a processor as described in FIGS. 5A-5B. Thecontrol circuit 2510 receives real-time sample measurements to provideanalyze time based information and assess, in real time, closure forcesapplied to the anvil 2516.

A current sensor 2536 can be employed to measure the current drawn bythe motor 2504. The force required to advance the I-beam 2514corresponds to the current drawn by the motor 2504. The force isconverted to a digital signal and provided to the control circuit 2510.

Using the physical properties of the instruments disclosed herein inconnection with FIGS. 1-14, and with reference to FIG. 14, the controlcircuit 2510 can be configured to simulate the response of the actualsystem of the instrument in the software of the controller. Adisplacement member can be actuated to move an I-beam 2514 in the endeffector 2502 at or near a target velocity. The surgical instrument 2500can include a feedback controller, which can be one of any feedbackcontrollers, including, but not limited to a PID, a State Feedback, LQR,and/or an Adaptive controller, for example. The surgical instrument 2500can include a power source to convert the signal from the feedbackcontroller into a physical input such as case voltage, pulse widthmodulated (PWM) voltage, frequency modulated voltage, current, torque,and/or force, for example.

The actual drive system of the surgical instrument 2500 is configured todrive the displacement member, cutting member, or I-beam 2514, by abrushed DC motor with gearbox and mechanical links to an articulationand/or knife system. Another example is the electric motor 2504 thatoperates the displacement member and the articulation driver, forexample, of an interchangeable shaft assembly. An outside influence isan unmeasured, unpredictable influence of things like tissue,surrounding bodies and friction on the physical system. Such outsideinfluence can be referred to as drag which acts in opposition to theelectric motor 2504. The outside influence, such as drag, may cause theoperation of the physical system to deviate from a desired operation ofthe physical system.

Before explaining aspects of the surgical instrument 2500 in detail, itshould be noted that the example aspects are not limited in applicationor use to the details of construction and arrangement of partsillustrated in the accompanying drawings and description. The exampleaspects may be implemented or incorporated in other aspects, variationsand modifications, and may be practiced or carried out in various ways.Further, unless otherwise indicated, the terms and expressions employedherein have been chosen for the purpose of describing the exampleaspects for the convenience of the reader and are not for the purpose oflimitation thereof. Also, it will be appreciated that one or more of thefollowing-described aspects, expressions of aspects and/or examples, canbe combined with any one or more of the other following-describedaspects, expressions of aspects and/or examples.

Various example aspects are directed to a surgical instrument 2500comprising an end effector 2502 with motor-driven surgical stapling andcutting implements. For example, a motor 2504 may drive a displacementmember distally and proximally along a longitudinal axis of the endeffector 2502. The end effector 2502 may comprise a pivotable anvil 2516and, when configured for use, a staple cartridge 2518 positionedopposite the anvil 2516. A clinician may grasp tissue between the anvil2516 and the staple cartridge 2518, as described herein. When ready touse the instrument 2500, the clinician may provide a firing signal, forexample by depressing a trigger of the instrument 2500. In response tothe firing signal, the motor 2504 may drive the displacement memberdistally along the longitudinal axis of the end effector 2502 from aproximal stroke begin position to a stroke end position distal of thestroke begin position. As the displacement member translates distally,an I-beam 2514 with a cutting element positioned at a distal end, maycut the tissue between the staple cartridge 2518 and the anvil 2516.

In various examples, the surgical instrument 2500 may comprise a controlcircuit 2510 programmed to control the distal translation of thedisplacement member, such as the I-beam 2514, for example, based on oneor more tissue conditions. The control circuit 2510 may be programmed tosense tissue conditions, such as thickness, either directly orindirectly, as described herein. The control circuit 2510 may beprogrammed to select a firing control program based on tissueconditions. A firing control program may describe the distal motion ofthe displacement member. Different firing control programs may beselected to better treat different tissue conditions. For example, whenthicker tissue is present, the control circuit 2510 may be programmed totranslate the displacement member at a lower velocity and/or with lowerpower. When thinner tissue is present, the control circuit 2510 may beprogrammed to translate the displacement member at a higher velocityand/or with higher power.

In some examples, the control circuit 2510 may initially operate themotor 2504 in an open-loop configuration for a first open-loop portionof a stroke of the displacement member. Based on a response of theinstrument 2500 during the open-loop portion of the stroke, the controlcircuit 2510 may select a firing control program. The response of theinstrument may include, a translation distance of the displacementmember during the open-loop portion, a time elapsed during the open-loopportion, energy provided to the motor 2504 during the open-loop portion,a sum of pulse widths of a motor drive signal, etc. After the open-loopportion, the control circuit 2510 may implement the selected firingcontrol program for a second portion of the displacement member stroke.For example, during the closed loop portion of the stroke, the controlcircuit 2510 may modulate the motor 2504 based on translation datadescribing a position of the displacement member in a closed-loop mannerto translate the displacement member at a constant velocity.

FIG. 15 illustrates a diagram 2580 plotting two example displacementmember strokes executed according to one aspect of this disclosure. Thediagram 2580 comprises two axes. A horizontal axis 2584 indicateselapsed time. A vertical axis 2582 indicates the position of the I-beam2514 between a stroke begin position 2586 and a stroke end position2588. On the horizontal axis 2584, the control circuit 2510 may receivethe firing signal and begin providing the initial motor setting at t₀.The open-loop portion of the displacement member stroke is an initialtime period that may elapse between t₀ and t₁.

A first example 2592 shows a response of the surgical instrument 2500when thick tissue is positioned between the anvil 2516 and the staplecartridge 2518. During the open-loop portion of the displacement memberstroke, e.g., the initial time period between t₀ and t₁, the I-beam 2514may traverse from the stroke begin position 2586 to position 2594. Thecontrol circuit 2510 may determine that position 2594 corresponds to afiring control program that advances the I-beam 2514 at a selectedconstant velocity (Vslow), indicated by the slope of the example 2592after t₁ (e.g., in the closed loop portion). The control circuit 2510may drive I-beam 2514 to the velocity Vslow by monitoring the positionof I-beam 2514 and modulating the motor set point 2522 and/or motordrive signal 2524 to maintain Vslow. A second example 2590 shows aresponse of the surgical instrument 2500 when thin tissue is positionedbetween the anvil 2516 and the staple cartridge 2518.

During the initial time period (e.g., the open-loop period) between t₀and t₁, the I-beam 2514 may traverse from the stroke begin position 2586to position 2596. The control circuit may determine that position 2596corresponds to a firing control program that advances the displacementmember at a selected constant velocity (Vfast). Because the tissue inexample 2590 is thinner than the tissue in example 2592, it may provideless resistance to the motion of the I-beam 2514. As a result, theI-beam 2514 may traverse a larger portion of the stroke during theinitial time period. Also, in some examples, thinner tissue (e.g., alarger portion of the displacement member stroke traversed during theinitial time period) may correspond to higher displacement membervelocities after the initial time period.

Referring to FIG. 16, a diagram 6040 plots an example of the forceapplied during a closure stroke to close the end effector 2502 aroundtissue grasped between the anvil 2516 and the staple cartridge 2518, theclosure force plotted as a function of the closure stroke displacement(d). The diagram 6040 comprises two axes. A vertical axis 6042 indicatesthe force to close (FTC) the end effector 2502 in newtons (N). Ahorizontal axis 6044 indicates a distance traveled by a closure membersuch as, for example, the closure tube 260 (FIG. 1) to cause the closureof the end effector 2502. During the closure stroke, the closure tube260 is translated distally (direction “DD”) to move the anvil 2516, forexample, relative to the staple cartridge 2518 in response to theactuation of the closure trigger 32 (FIG. 1) in the manner described inthe aforementioned reference U.S. Patent Application Publication No.2014/0263541. In other instances, the closure stroke involves moving astaple cartridge relative to an anvil in response to the actuation ofthe closure trigger 32. In other instances, the closure stroke involvesmoving the staple cartridge and the anvil in response to the actuationof the closure trigger 32.

The diagram 6040 indicates that the force to close (FTC) the endeffector 2502 increases as the closure tube 260 travels distally. Theforce to close (FTC) reaches a maximum force (F_(max)) at a distance (d)traveled by the closure tube 260 from a starting position. An endeffector 300, which is similar in many respects to the end effector2502, compresses tissue to a maximum threshold corresponding to themaximum force (F_(max)). The maximum force (F_(max)) depends, at leastin part, on the thickness of the tissue grasped by the end effector2502. In one example, the closure member is configured to travel adistance (d1) of about 0.210″ (5.334 mm) to reach a maximum force(F_(max)) of about 160 pound-force (711.715 newtons).

FIG. 16 also depicts a diagram 6046 that plots an example of the forceapplied to fire (FTF) the surgical instrument 2500. The force to fire(FTF) can be applied to advance the I-beam 2514 during a firing strokeof the surgical instrument 2500. The diagram 6046 comprises two axes. Avertical axis 6048 indicates the force, in newtons (N), applied toadvance the I-beam 2514 during the firing stroke. The I-beam 2514 isconfigured to advance the knife 2509 and motivate the drivers 2511 todeploy the staples 2505 during the firing stroke. A horizontal axis 6050indicates the time in seconds.

The I-beam 2514 is advanced from a starting time (t=0). The advancementof the I-beam 2514 is initiated when the force to close (FTC) the endeffector 2502 reaches a maximum force (F_(max)). Alternatively, asillustrated in FIG. 22, a waiting period can be applied prior tostarting the firing stroke. The waiting period allows fluid egress fromthe compressed tissue which reduces the thickness of the compressedtissue yielding a reduction in the maximum force (F_(max)).

The diagram 6046 indicates that the force to fire (FTF) the surgicalinstrument 2500 increases to a maximum force (F₂) at the top of thehighest peak 6052. The maximum force (F₂) is at an initial section ofthe firing stroke when the wedge sled 2513. The top of the lowest peak6054 represents a maximum force (F₁), which occurs at final section ofthe firing stroke. The maximum force (F₁) is applied to the I-beam 2514during engagement of the wedge sled 2513 with the distal staple drivers2511. In addition, intermediate peaks 6056, which occur at anintermediate section of the firing stroke, between the peak 6052 and thepeak 6054, outline a downward slope of 6053 the force needed to fire(FTF) the surgical instrument 2500 during the intermediate section ofthe firing stroke. The downward slope 6053 begins at a time (t₁)corresponding to the maximum force (F₁) at the top of the highest peak6052. The downward slope 6053 generally results from a gradual reductionin the load as the I-beam 2514 advances the wedge sled 2513 through theintermediate portion of the firing stroke beyond the time (t₁).

FIG. 17 illustrates a logic flow diagram showing one example of aprocess 6030 of a control program or logic configuration that may beexecuted by the surgical instrument 2500 (e.g., the control circuit2510) to implement an I-beam stroke responsive to tissue conditionsand/or staple cartridge type. The control circuit 2510 may receive 6031a firing signal. The firing signal may be received 6031 from the trigger32 (FIG. 1) or other suitable actuation device. For example, a clinicianmay place the end effector 2502, clamp tissue between the anvil 2516 andstaple cartridge 2518 and then actuate the trigger 32 to begin an I-beamstroke. The trigger 32 may be configured to provide the firing signal tothe control circuit 2510 upon actuation.

The control circuit 2510, in response to the firing signal, may provide6032 an initial motor setting. For example, the initial motor settingmay be a motor set point 2522 provided to the motor controller 2508. Themotor controller 2508 may translate the initial motor set point 2522into a PWM signal, voltage signal, or other suitable motor drive signalto drive the motor 2504. In some examples, (e.g., when the controlcircuit 2510 directly generates the motor drive signal 2524), theinitial motor setting may be a motor drive signal 2524 provided directlyto the motor 2504. The initial motor setting may correspond to aparticular motor velocity, power, or other suitable variable. In someexamples where the motor 2504 is a brushed DC motor, the initial motorsetting may be a signal having a constant voltage. In some exampleswhere the motor is a brushless DC motor, the initial motor setting maybe a signal or set of signals having a constant phase, duty cycle, etc.

The control circuit 2510 may receive 6036 I-beam member movement data.E-member beam movement data may comprise information (e.g., from theposition sensor 2534) that describes the position and/or movement of theI-beam 2514. Although receiving 6036 I-beam member movement data may bea portion of the process 6030, in some examples, the control circuit2510 may receive 6036 I-beam member movement data while the I-beam 2514is in motion. For example, when the position sensor 2534 is an encoder,the control circuit 2510 may receive pulse signals from the encoderwhile the I-beam 2514 is moving with each pulse signal representing aquantum of motion. Also, in examples where the motor 2504 is a steppermotor, the control circuit 2510 may derive I-beam member movement databased on the total number of steps that the control circuit 2510instructs the motor 2504 to execute.

I-beam member movement data may indicate a distance that the I-beam 2514moved during the initial time period, which may reflect the tissueconditions such as the thickness and/or toughness of the tissue presentbetween the anvil 2516 and the staple cartridge 2518 because differenttypes of tissue will offer different levels of resistance. For example,thicker or tougher tissue may provide more mechanical resistance to theknife and staples. More mechanical resistance may cause the motor 2504to run more slowly while the initial motor setting is held substantiallyconstant. Similarly, thinner or weaker tissue may provide lessmechanical resistance to the knife and staples. This may cause the motorto run faster and traverse more distance while the initial motor settingis held substantially constant.

After the initial motor setting is provided, the instrument 2500 may runin an open-loop configuration in a diagnostic first portion (1a) of zone1, as illustrated in FIG. 18. For example, the motor drive signal 2524may be held substantially constant. As a result, the actual propertiesof the motor 2504, such as motor velocity, may drift based on factorsincluding tissue conditions (e.g., tissue thickness, tissue toughness,etc.) For example, when thicker or tougher tissue is present between theanvil 2516 and the staple cartridge 2518, the tissue may provide moremechanical resistance to the knife and/or staples, which may tend toslow the velocity of the I-beam 2514 as the motor setting is heldsubstantially constant.

The control circuit 2510 may be configured to maintain the initial motorsetting for an open-loop portion of the I-beam stroke. In the example ofFIG. 17, the open-loop portion of the I-beam stroke may continue untilthe I-beam 2514 has traversed an initial distance. Accordingly, thecontrol circuit 2510 may be configured to maintain the initial motorsetting until the I-beam has traversed the initial distance. The initialdistance may be, for example, a predetermined portion of the totaldistance between the firing stroke begin position and the firing strokeend position (e.g., ⅙, ¼, ⅓, etc.). In one example, the initialopen-loop distance is a first initial portion (1a) of zone 1 spanning adistance of about 0.200″ (5.08 millimeters) from the stroke beginposition 2527 (FIG. 13). The control circuit 2510 may determine 6034from the received I-beam member movement data whether the I-beam 2514has traversed the initial distance. If not, the control circuit 2510 maycontinue to provide 6032 the initial motor setting and receive 6036additional I-beam member movement data.

In some examples, the initial open-loop distance is a diagnostic firstportion (1a) of zone 1 spanning a distance selected from range of about1 millimeter to about 10 millimeters. In some examples, the initialopen-loop distance spans a distance selected from range of about 3millimeters to about 7 millimeters.

The process 6030 may proceed if the control circuit 2510 determines 6034that the I-beam has traversed the initial distance. In some examples,the control circuit 2510 may maintain a running counter or timer 2531(FIG. 14) while the initial distance is traversed. When the controlcircuit 2510 determines that the I-beam has traversed the initialdistance, the control circuit 2510 may stop the timer 2531. The controlcircuit 2510 may determine 6039 an I-beam velocity over the initialdistance. The control circuit 2510 may find the I-beam velocity bytaking the initial distance divided by the time required to traverse thedistance.

Alternatively, in some examples, the open-loop portion may be an initialtime period, which may also be referred to as an open-loop time period.The initial time period may be of any suitable length including, forexample, 100 milliseconds. A position sensor such as, for example, theposition sensor 2534 (FIG. 14) may track the position of the I-beam 2514during the initial time period. The control circuit 2510 may determinean I-beam velocity over the initial time period. The control circuit2510 may find the I-beam velocity by taking the distance traversed bythe I-beam 2514 during the initial time period divided by the initialtime period. The velocity of the I-beam 2514 in the diagnostic firstportion (1a) of zone 1 can be indicative of the tissue conditions suchas the thickness and/or toughness of the tissue present between theanvil 2516 and the staple cartridge 2518.

Alternatively, in some examples, current (I) drawn by the motor 2504 inthe open-loop portion can be used to assess the tissue conditions suchas the thickness and/or toughness of the tissue present between theanvil 2516 and the staple cartridge 2518. A sensor such as, for example,a current sensor can be employed to track the current (I) drawn by themotor 2504 in the open-loop portion. One example of a current sensor2536 is shown in FIG. 14.

Returning now to FIG. 17, the control circuit 2510 may select 6038 afiring control program or configuration, for example, based on thedetermined I-beam velocity and/or the current (I) drawn by the motor2504 in the open-loop portion in the diagnostic first portion (1a) ofzone 1. The control circuit 2510 may execute 6041 the selected firingcontrol program or logic configuration.

In some examples, the firing control program may determine a targetvalue for the movement of the I-beam 2514 during the remainder of theI-beam stroke. FIG. 18 illustrates a diagram 6100 plotting velocityversus distance traveled along a firing stroke for three example I-beamstrokes 6106, 6108, 6110, which can be implemented by the firing controlprograms selected at 6038. The diagram 6100 includes two axes. Ahorizontal axis 6102 represents the firing stroke displacement inmillimeters. A vertical axis 6104 indicates velocity of the I-beam 2514in millimeters per second. As illustrated, in FIG. 18, the examples6106, 6108, 6110 initially have the same I-beam velocity in thediagnostic first portion (1a) of zone 1 of the firing stroke distance.

In the example 6106 of FIG. 18, the firing control program is configuredto maintain the velocity of the I-beam 2514 at a predetermined constant,or substantially constant, velocity. The constant velocity may beselected based on the movement of the I-beam during the diagnostic firstportion (1a) of zone 1. In some examples, the firing control program mayinclude driving the I-beam 2514 with a constant power. The controlcircuit 2510 may implement 6041 the firing control program or logicconfiguration previously selected 6038. For example, the control circuit2510 may drive the I-beam 2514 with constant velocity by monitoring theposition of the I-beam 2514 indicated by the position sensor 2534 andmodulating the motor set point 2522 and/or motor drive signal 2524 tomaintain a constant velocity. Similarly, the control circuit 2510 maydrive the I-beam 2514 with constant power by monitoring the voltageand/or current drawn by the motor 2504 and modulating the motor setpoint 2522 and/or motor drive signal 2524 to maintain a constant powerdraw.

As described above in connection with the diagram 6046 of FIG. 16, theforce to fire (FTF) gradually decreases as the I-beam 2514 is advancedduring the firing stroke. As such, the force to fire (FTF) the I-beam2514 is generally higher at the beginning of the firing stroke than themiddle of the firing stroke, and generally higher at the middle of thefiring stroke than the end of the firing stroke. Maintaining a reducedvelocity of the I-beam 2514 in portions of the firing stroke where theI-beam 2514 experiences higher loads improves the performance of themotor 2504 and the energy source 2512. First, the total current (I)drawn by the motor 2504 during the firing stroke is reduced, whichprolongs the life of the energy source 2512 (FIG. 14). Second, reducingthe velocity of the I-beam 2514 in portions of the firing stroke withthe higher loads protects the motor 2504 from stalling. The increasedresistance may cause the motor 2504 to stall. Stalling is a conditionwhen the motor stops rotating. This condition occurs when the loadtorque is greater than the motor shaft torque.

To reduce the load or force to fire (FTF) applied to the I-beam 2514,alternative firing control programs are employed by the control circuit2510. Two of the alternative firing control programs are represented inthe examples 6108, 6110 of FIG. 18. FIG. 19B illustrates a logic flowdiagram showing one example of a process 6131 of a control program orlogic configuration that may be selected 6038 and executed 6041 by thesurgical instrument 2500 (e.g., the control circuit 2510) at 6041 toimplement an I-beam stroke responsive to tissue conditions and/or staplecartridge type. The firing process 6131 may include driving the I-beam2514 at a velocity that increases linearly as the I-beam 2514 isadvanced along the firing stroke, as illustrated in an example 6108 ofFIG. 18.

The control circuit 2510 controls 6132 the motor 2504 to reach astarting velocity (v1) at a predetermined position at a starting point6101. The control circuit 2510 drives 6134 the I-beam 2514 with avelocity that increases linearly at a predetermined rate as the I-beam2514 is advanced along the firing stroke by modulating the motor setpoint 2522 and/or motor drive signal 2524 to yield a linear, orsubstantially linear, increase in the velocity of the I-beam 2514 as theI-beam 2514 is advanced along the firing stroke. The velocity rate ofthe I-beam 2514 is maintained 6135 until the end of the firing stroke.

The control circuit 2510 may monitor the position of the I-beam 2514indicated by the position sensor 2534 and time as indicated by the timer2531. The data from the position sensor 2534 and the timer 2531 can beemployed by the control circuit 2510 to sample the velocity of theI-beam 2514 at discrete positions along the firing stroke. The sampledvelocity can be compared against predetermined thresholds to determinehow to modulate the motor set point 2522 and/or motor drive signal 2524to yield the linear, or substantially linear, increase in the velocityof the I-beam 2514 as the I-beam 2514 is advanced along the firingstroke. In some examples, the velocity of the I-beam 2520 is sampled inintervals of 1 millimeter.

In some examples, the absolute positioning system 1100 (FIGS. 10-12) canbe employed to sense the position of the I-beam 2514, and the velocityof the I-beam 2520 is sampled in intervals defined by the revolution(s)of the sensor element 1126.

In some examples, the control circuit 2510 is configured to increase thevelocity of the I-beam 2514 at a constant, or substantially constant,rate as the I-beam 2514 is advanced through the firing stroke. The rateof increase of the velocity of the I-beam 2514 may be selected based onthe movement of the I-beam during the diagnostic first portion (1a) ofzone 1. In one example, a look-up table can be employed to determine therate of increase of the velocity of the I-beam 2514 based onmeasurements representing the movement of the I-beam during thediagnostic first portion (1a) of zone 1.

As illustrated in FIG. 18, the linear increase in the velocity of theI-beam 2514 begins at a starting point 6101 representing a startingvelocity (v1) at a predetermined position in the beginning of a secondportion (1b) of zone 1. The starting velocity v1 also can be determinedbased the movement of the I-beam 2514 during the diagnostic firstportion (1a) of zone 1. In one example, a look-up table can be employedto determine the starting velocity v1 based on measurements representingthe movement of the I-beam 2514 during the diagnostic first portion (1a)of zone 1. Notably, the starting velocity (v1) of the example 6108 issignificantly lower than the constant velocity of the example 6110,which yields a reduced force to fire (FTF) in the example 6108.

The control circuit 2510 also can be configured to determine thestarting velocity v1 and/or the rate of increase of the velocity of theI-beam 2514 based on tissue conditions. As described above, the tissueconditions such as the thickness and/or toughness of the tissue presentbetween the anvil 2516 and the staple cartridge 2518 can influence themovement of the I-beam 2514 because different types of tissue will offerdifferent levels of resistance. For example, thicker or tougher tissuemay provide more mechanical resistance to the I-beam 2520. Moremechanical resistance may cause the motor 2504 to run more slowly whilethe initial motor setting is held substantially constant. Similarly,thinner or weaker tissue may provide less mechanical resistance to theI-beam 2520. This may cause the motor to run faster and traverse moredistance while the initial motor setting is held substantially constant.

In the example 6110 of FIG. 18, a firing control program may includedriving or maintaining the I-beam 2514 at a plurality of constant, orsubstantially constant, velocities at a plurality of discrete orcontinuous portions or zones within the firing stroke to reduce the loador force to fire (FTF) as the I-beam 2514 is advanced through the firingstroke. The firing stroke distance is divided into three zones: zone 1,zone 2, and zone 3. The load experienced by the I-beam 2514 in zone 1 isgreater than zone 2, and the load experienced by the I-beam 2514 in zone2 is greater than zone 3. To reduce the force to fire (FTF), asillustrated in the example 6110 of FIG. 18, the I-beam 2514 is driven atthree constant, or substantially constant, velocities v1, v2, and v3 inzone 1, zone 2, and zone3, respectively.

In some examples, the number of zones and corresponding velocities canbe more or less than three depending on the staple cartridge size and/ortissue conditions. The positioning of I-beam stroke zones in FIG. 18 isjust one example. In some examples, different zones may begin atdifferent positions along the end effector longitudinal axis 2515, forexample, based on the positioning of tissue between the anvil 2516 andthe staple cartridge 2518.

FIG. 19A illustrates a logic flow diagram showing one example of aprocess 6111 of a control program or logic configuration that may beselected 6038 and executed 6041 by the surgical instrument 2500 (e.g.,the control circuit 2510) at 6041 to implement an I-beam strokeresponsive to tissue conditions and/or staple cartridge type. In zone 1,where the I-beam 2514 experiences the highest load, the I-beam 2514 isdriven at a slow constant, or substantially constant, velocity (v1). Thecontrol circuit 2510 controls 6114 the motor 2504 to reach a velocity(v1) at starting point 6101 (FIG. 18), which represents a predeterminedposition at the beginning of a second portion (1b) of zone 1. Thecontrol circuit 2510 maintains 6116 the velocity of the I-beam 2514 atthe velocity (v1) for the remainder of zone 1 beginning at the startingpoint 6101. At 6115, if the I-beam 2514 is in zone 1, the controlcircuit 2510 maintains 6116 the velocity of the I-beam 2514 at thevelocity (v1). If, however, the I-beam 2514 is no longer in zone 1, thecontrol circuit 2510 controls 6117 the motor 2504 to reach a velocity(v2) at the starting point 6103 (FIG. 18), which represents apredetermined position in zone 2. Notably, the velocity (v1) issignificantly lower than the constant velocity of the example 6106,which reduces the force to fire (FTF) in the example 6110 relative tothe example 6106.

In zone 2, where the I-beam 2514 experiences an intermediate load, theI-beam 2514 is maintained 6119 at a constant, or substantially constant,velocity (v2) that is higher than the velocity (v1) for the remainder ofzone 2. If the control circuit 2510 determines 6118 that the I-beam 2514is in zone 2, the control circuit 2510 maintains 6119 the velocity ofthe I-beam 2514 at the velocity (v2). If, however, the I-beam 2514 is nolonger in zone 2, the control circuit 2510 controls 6120 the motor 2504to reach a predetermined velocity (v3) at the starting point 6105 (FIG.18), which represents a predetermined position in zone 3. The controlcircuit 2510 maintains 6121 the velocity (v3) until the I-beam 2514reaches an end of stroke 6122.

As described above, the control circuit 2510 may drive the I-beam 2514with a constant velocity by monitoring the position of the I-beam 2514indicated by the position sensor 2534 and modulating the motor set point2522 and/or motor drive signal 2524 to maintain a constant velocity.

The control circuit 2510 may select the velocity (v1), velocity (v2),and/or velocity (v3) based on the movement of the I-beam 2514 during thediagnostic first portion (1a) of zone 1. In some examples, the controlcircuit 2510 may select the velocity (v1), velocity (v2), and/orvelocity (v3) based on the determined I-beam velocity and/or the current(I) drawn by the motor 2504 in the open-loop portion in the diagnosticfirst portion (1a) of zone 1. In one example, a look-up table can beemployed to determine the velocity (v1), velocity (v2), and/or velocity(v3) based on measurements representing the movement of the I-beam 2514during the diagnostic first portion (1a) of zone 1.

In one example, the control circuit 2510 may select the constant, orsubstantially constant, velocity of a zone of the firing stroke based onmovement of the I-beam 2514 in one or more previous zones of the firingstroke. For example, the control circuit 2510 may select the velocity ofsecond or intermediate zone based on the movement of the I-beam 2514 ina first zone. Also, the control circuit 2510 may select the velocity ofa third zone based on the movement of the I-beam 2514 in a first zoneand/or a second zone.

As indicated in the example of FIG. 18, the control circuit 2510 can beconfigured to maintain a linear, or substantially linear, transitionfrom the velocity (v1) to the higher velocity (v2) in the initialportion of zone 2. The control circuit 2510 may increase the velocity ofthe I-beam 2514 at a constant rate to yield the linear, or substantiallylinear, transition from the velocity (v1) to the higher velocity (v2).Alternatively, the control circuit 2510 can be configured to maintain anon-linear transition from the velocity (v1) to the higher velocity (v2)in the initial portion of zone 2.

In addition, the control circuit 2510 can be configured to maintain alinear, or substantially linear, transition from the velocity (v2) tothe higher velocity (v3) in the initial portion of zone 3. The controlcircuit 2510 may increase the velocity of the I-beam 2514 at a constantrate to yield the linear, or substantially linear, transition from thevelocity (v2) to the higher velocity (v3). Alternatively, the controlcircuit 2510 can be configured to maintain a non-linear transition fromthe velocity (v2) to the higher velocity (v3) in the initial portion ofzone 3.

As illustrated in diagram 6230 of FIG. 20, the force to fire (FTF)gradually decreases as the I-beam 2514 is advanced during the firingstroke. As such, the force to fire (FTF) applied to the I-beam 2514 isgenerally higher at the beginning of the firing stroke than the middleof the firing stroke, and generally higher at the middle of the firingstroke than the end of the firing stroke. Running the motor 2504 at areduced or low duty cycle in portions of the firing stroke where theI-beam 2514 experiences higher loads improves the performance of themotor 2504 and the energy source 2512. As described above, the totalcurrent (I) drawn by the motor 2504 during the firing stroke is reduced,which prolongs the life of the energy source 2512 (FIG. 14). Second,running the motor 2504 at a reduced duty cycle in portions of the firingstroke with the higher loads protects the motor 2504 from stalling.

In some examples, a firing control program may determine a target valuefor the duty cycle of the motor 2504 based on the position of the I-beam2514 along the firing stroke. FIG. 20 illustrates a diagram 6200plotting the duty cycle of the motor 2504 versus distance traveled alonga firing stroke for three example firing strokes 6206, 6208, 6210, whichcan be implemented by the firing control programs selected at 6038. Inthe diagram 6200, a horizontal axis 6202 represents the firing strokedisplacement in millimeters. The vertical axis 6204 indicates the dutycycle of the motor 2504 expressed as a percentage. As illustrated, inFIG. 20, the examples 6206, 6208, 6210 initially have the same dutycycle in a diagnostic first portion (1a) of zone 1 of the firing strokedistance. FIG. 20 illustrates a diagram 6230 which includes examples6206′, 6208′, and 6210′ corresponding to the examples 6206, 6208, and6210 of the diagram 6200, respectively. In the diagram 6200, ahorizontal axis 6234 represents the time in seconds. The vertical axis6232 indicates the force to fire (FTF) applied as the I-beam 2514 isadvanced through the firing stroke.

In the example 6206 of FIG. 20, a firing control program is configuredto run the motor 2504 at a predetermined constant, or substantiallyconstant, duty cycle. The constant duty cycle may be selected based onthe movement of the I-beam during the diagnostic first portion (1a) ofzone 1. The example 6206′ represents the force to fire (FTF) associatedrunning the motor 2504 during the firing stroke at a predeterminedconstant, or substantially constant, duty cycle.

To reduce the load or force to fire (FTF), as illustrated in the forceto fire (FTF) profiles of examples 6208′ and 6210′, alternative firingcontrol programs are selected at 6038 corresponding to the examples 6208and 6210 of the diagram 6100. As depicted in the diagram 6230, theexamples 6208′ and 6210′ have lower force to fire (FTF) profiles thanthe example 6206′ and lower maximum force thresholds (F₁) and (F₂) thanthe maximum force threshold (F₃) of the example 6206′.

The example 6210′ represents the force to fire (FTF) profile associatedwith running the motor 2504 in a closed-loop. During the closed loopportion of the stroke, the control circuit 2510 may modulate the dutycycle of the motor 2504 based on translation data describing a positionof the I-beam 2514. During closed loop, the control circuit 2510 isconfigured to gradually increase the duty cycle of the motor 2504 as theI-beam 2514 is advanced along the firing stroke.

The control circuit 2510 may monitor the position of the I-beam 2514indicated by the position sensor 2534. The data from the position sensor2534 can be employed by the control circuit 2510 to set the duty cycleof the motor 2504. In some examples, the duty cycle of the motor 2504 ischanged by the control circuit 2510 in intervals of 1 millimeter. In oneexample, the control circuit 2510 is configured to maintain asubstantially linear increase in the duty cycle of the motor 2504 as theI-beam 2514 is advanced through the firing stroke.

In some examples, the absolute positioning system 1100 (FIGS. 10-12) canbe employed to sense the position of the I-beam 2514, and the duty cycleof the motor 2504 can be set based on the position of the I-beam 2514 asassessed by the revolution(s) of the sensor element 1126.

In some examples, the control circuit 2510 is configured to increase theduty cycle of the motor 2504 at a substantially constant rate as theI-beam 2514 is advanced through the firing stroke. The rate of increaseof the duty cycle of the motor 2504 may be selected based on themovement of the I-beam 2514 during a diagnostic time (t1) in thediagnostic first portion (1a) of zone 1. In one example, a look-up tablecan be employed to determine the rate of increase of the velocity of theI-beam 2514 based on measurements representing the movement of theI-beam 2514 during a diagnostic time (t1) in the diagnostic firstportion (1a) of zone 1.

In one example, a look-up table can be employed to determine the dutycycle of the motor 2504 based on measurements representing the movementof the I-beam 2514 during the diagnostic first portion (1a) of zone 1.The control circuit 2510 also can be configured to determine the dutycycle of the motor 2504 at various positions of the I-beam 2514 alongthe firing stroke based on tissue conditions. As described above, thetissue conditions such as the thickness and/or toughness of the tissuepresent between the anvil 2516 and the staple cartridge 2518 caninfluence the movement of the I-beam 2514 because different types oftissue will offer different levels of resistance.

An alternative example 6208′ represents the reduced force to fire (FTF)profile associated with running the motor 2504 at a plurality ofconstant, or substantially constant, duty cycles at a plurality ofdiscrete or continuous portions or zones within the firing stroke. Asdescribed above in connection with the diagram 6100, the firing strokedistance is divided into three zones: zone 1, zone 2, and zone 3. Theload experienced by the I-beam 2514 in zone 1 is greater than zone 2,and the load experienced by the I-beam 2514 in zone 2 is greater thanzone 3. To reduce the force to fire (FTF), the motor 2504 is run atthree different duty cycles set at predetermined positions at points6201, 6203, and 6205 of zone 1, zone 2, and zone 3, respectively, asillustrated in FIG. 20. In some examples, the number of zones andcorresponding duty cycles can be more or less than three depending onthe staple cartridge size and/or tissue conditions. The positioning ofI-beam stroke zones in FIG. 20 is just one example. In some examples,different zones may begin at different positions along the end effectorlongitudinal axis 2515, for example, based on the positioning of tissuebetween the anvil 2516 and the staple cartridge 2518.

In zone 1, where the I-beam 2514 experiences the highest load, the motor2504 is run at a low duty cycle. As indicated in the example 6208 ofFIG. 20, the control circuit 2510 is configured to maintain the dutycycle of the motor 2504 at about 45%, for example, for the remainder ofzone 1 beginning at the point 6201, which represents a predeterminedposition in the beginning of a second portion (1b) of zone 1.

In zone 2, where the I-beam 2514 experiences an intermediate load, themotor 2504 is run at an intermediate duty cycle greater than the dutycycle maintained in zone 1. At the onset of zone 2, the control circuit2510 is configured to increase the duty cycle of the motor 2504 up to apredetermined duty cycle, which is maintained at a constant, orsubstantially constant, value by the control circuit 2510 for theremainder of zone 2. As indicated in the example 6208 of FIG. 20, thecontrol circuit 2510 is configured to maintain the duty cycle of themotor 2504 at about 75%, for example, for the remainder of zone 2beginning at the point 6203, which represents a predetermined position.

In zone 3, where the I-beam 2514 experiences the lowest load, the motor2504 is run at a duty cycle greater than the duty cycle maintained inzone 2. At the onset of zone 3, the control circuit 2510 is configuredto increase the duty cycle of the motor 2504 up to a predetermined dutycycle, which is maintained at a constant, or substantially constant,value by the control circuit 2510 for the remainder of zone 3. Asindicated in the example 6208 of FIG. 20, the control circuit 2510 isconfigured to maintain the duty cycle of the motor 2504 at about 100%,for example, for the remainder of zone 3 beginning at the point 6205,which represents a predetermined position.

The control circuit 2510 may select the duty cycles for zones 1, 2, and3 based on the movement of the I-beam 2514 during the diagnostic firstportion (1a) of zone 1. In some examples, the control circuit 2510 mayselect the duty cycles for zones 1, 2, and 3 based on the determinedI-beam velocity and/or the current (I) drawn by the motor 2504 in theopen-loop portion in the diagnostic first portion (1a) of zone 1. In oneexample, a look-up table can be employed to determine the duty cyclesfor zones 1, 2, and 3 based on measurements representing the movement ofthe I-beam 2514 during the diagnostic first portion (1a) of zone 1.

Although the firing control program or logic configuration of theexample 6208 depicts three steps with constant, or substantiallyconstant, duty cycles at 45%, 75%, and 100%, other duty cycles arecontemplated by the present disclosure. In one example, as illustratedin a diagram 6300 of FIG. 21, a firing control program may includerunning the motor 2504 at a duty cycle of about 33% in a first zone ofthe firing stroke, a duty cycle of about 66% in a second zone of thefiring stroke, and a duty cycle of about 100% at a third zone of thefiring stroke. The different duty cycles can be set to begin atdifferent I-beam positions along the firing stroke, for example.

In one example, the control circuit 2510 may select the constant, orsubstantially constant, duty cycle of the motor 2504 of a zone of thefiring stroke based on movement of the duty cycle of the motor 2504 inone or more previous zones of the firing stroke. For example, thecontrol circuit 2510 may select the duty cycle of a second orintermediate zone based on the duty cycle in a first zone. Also, thecontrol circuit 2510 may select the duty cycle of a third zone based onthe duty cycle in a first zone and/or a second zone.

The diagram 6300 illustrates a plot of the duty cycle of the motor 2504versus distance traveled along a firing stroke for an example firingstroke 6310, which can be implemented by a firing control programsselected at 6038. In the diagram 6300, a horizontal axis 6302 representsthe firing stroke displacement in millimeters. The vertical axis 6304indicates the duty cycle of the motor 2504 expressed as a percentage. Asillustrated in the FIG. 21, the example 6310 indicates running the motor2504 at a duty cycle of about 33% in zone 1 of the firing stroke, a dutycycle of about 66% in zone 2 of the firing stroke, and a duty cycle ofabout 100% at zone 3 of the firing stroke. Other values for the dutycycles at zone 1, zone 2, and/or zone 3 are contemplated by the presentdisclosure.

In one example, the motor 2504 can be run, in an initial zone of thefiring stroke, at a duty cycle selected from a range of about 25% toabout 50%. In one example, the motor 2504 can be run, in intermediatezone of the firing stroke, at a duty cycle selected from a range ofabout 50% to about 80%. In one example, the motor 2504 can be run, finalzone of the firing stroke, at a duty cycle selected from a range ofabout 75% to about 100%.

In some examples, the motor 2504 may be a brushless direct current (DC)electric motor and the motor drive signal 2524 may comprise apulse-width-modulated (PWM) signal provided to one or more statorwindings of the motor 2504. FIG. 21 further illustrates a diagram 6350depicting an example 6360 indicating pulse-width modulated signalscorresponding to the motor duty cycles of zone 1, zone 2, and zone3 ofthe example 6310. The diagram 6350 includes two axes. A horizontal axis6354 represents the firing stroke displacement in millimeters. Avertical axis 6352 indicates pulse-width modulation signals.

A firing control program of the example 6310 may vary the pulse-width ofthe signal supplied to the motor 2504 depending on the position of theI-beam 2514 along the firing stroke. A first pulse width can bemaintained in zone 1. A second pulse width greater than the first pulsewidth can be maintained in zone 2. A third pulse width greater than thesecond pulse-width can be maintained in zone 3.

In various examples, the above-described zones 1, 2, and 3 of the firingstroke can be equal, or substantially equal, in distance. In otherwords, each of the three zones can be about a third of the totaldistance traveled by the I-beam 2514 during a firing stroke. In otherexamples, the firing stroke distance can be divided into more or lessthan three zones that are equal or different in distance.

Referring to FIG. 22, a diagram 6400 plots an example 6408 of the forceapplied during a closure stroke to close the end effector 2502 relativeto tissue grasped between the anvil 2516 and the staple cartridge 2518,the closure force plotted as a function of time. The diagram 6400comprises two axes. A vertical axis 6402 indicates the force to close(FTC) the end effector 2502 in newtons (N). A horizontal axis 6404indicates time in seconds. During the closure stroke, the closure tube260 is translated distally (direction “DD”) to move the anvil 2516, forexample, relative to the staple cartridge 2518 in response to theactuation of the closure trigger 32 (FIG. 1) in the manner described inthe aforementioned reference U.S. Patent Application Publication No.2014/0263541. In other instances, the closure stroke involves moving astaple cartridge relative to an anvil in response to the actuation ofthe closure trigger 32. In other instances, the closure stroke involvesmoving the staple cartridge and the anvil in response to the actuationof the closure trigger 32.

The example 6408 indicates that the force to close (FTC) the endeffector 2502 increases during an initial clamping time period ending ata time (t₀). The force to close (FTC) reaches a maximum force (F₃) atthe time (t₀). The initial clamping time period can be about one second,for example. A waiting period can be applied prior to initiating afiring stroke. The waiting period allows fluid egress from tissuecompressed by the end effector 2502, which reduces the thickness of thecompressed tissue yielding a smaller gap between the anvil 2516 and thestaple cartridge 2518 and a reduced closure force (F₁) at the end of thewaiting period. In some examples, a waiting period selected from a rangeof about 10 seconds to about 20 seconds is typically employed. In theexample 6408, a period of time of about 15 seconds is employed. Thewaiting period is followed by the firing stroke, which typically lasts aperiod of time selected from a range of about 3 seconds, for example, toabout 5 seconds, for example. The force to close (FTC) decreases as theI-beam 2514 is advanced relative to the end effector through the firingstroke.

FIG. 22 also depicts a diagram 6450 that plots three examples 6456,6458, 6460 of the force applied to advance the I-beam 2514 during thefiring stroke of the surgical instrument 2500. The diagram 6450comprises two axes. A vertical axis 66452 indicates the force, innewtons (N), applied to advance the I-beam 2514 during the firingstroke. The I-beam 2514 is configured to advance the knife 2509 andmotivate the drivers 2511 to deploy the staples 2505 during the firingstroke. A horizontal axis 6050 indicates the time in seconds.

The I-beam 2514 is advanced from the stroke begin position 2527 (FIG.13) at a starting time (t=0) to the stroke end position 2528 (FIG. 13).As the I-beam 2514 is advanced through the firing stroke, the closureassembly surrenders control of the staple cartridge 2518 and the anvil2516 to the firing assembly, which causes the force to fire (FTF) toincrease and the force to close (FTC) to decrease.

In an alternative example 6406, a stiffer anvil 6410 (FIG. 23) isemployed. The stiffness of the anvil 6410 of the example 6406 is greaterthan the stiffness of the anvil of the example 6408. The stiffer anvil6410 yields greater maximum closure forces (F₄) at time (t₀) and (F₂) atthe end of the waiting period than the maximum closure forces (F₃) and(F₁) associated with the anvil of the example 6408. Because of theincreased stiffness, the ability of the anvil 6410 of the example 6406to deflect or bend away from the compressed tissue is less than that ofthe anvil of the example 6408. Accordingly, the anvil 6410 of theexample 6406 experiences a greater load than the anvil of the example6408 throughout the closure stroke.

The examples 6456 and 6458 of the diagram 6450 are force to fire (FTF)corresponding to the examples 6406 and 6408, respectively, of thediagram 6400. The stiffer anvil 6410 of the examples 6406 and 5458,while encountering a greater force to close (FTC) profile than the anvilof the examples 6408 and 6456, experiences a lesser force to fire (FTF)profile. In the examples 6456 and 6458, the force to fire (FTF) profileis reduced by about 20% because of the increased stiffness of the anvil6410. Various techniques can be employed in increasing the stiffness ofan anvil as described in U.S. patent application Ser. No. 15/385,922,titled SURGICAL INSTRUMENT WITH MULTIPLE FAILURE RESPONSE MODES, andfiled Dec. 21, 2019, the entire disclosure of which is herebyincorporated herein by reference.

The stiffer anvil 6410 has an elongate anvil body 6412 that has an upperbody portion 6414 that has an anvil cap 6416 attached thereto. In theaspect depicted in FIG. 22, the anvil cap 6416 is roughly rectangular inshape and has an outer cap perimeter 6418. The perimeter 6418 of theanvil cap 6416 is configured to be inserted through thecorrespondingly-shaped opening formed in an upper body portion andreceived on axially extending internal ledge portions of the anvil body6412. The anvil body 6412 and the anvil cap 6416 may be fabricated fromsuitable metal that is conducive to welding. A first weld 6420 mayextend around the entire cap perimeter 6418 of the anvil cap 6416 or itmay only be located along the long sides 6422 of the anvil cap 6416 andnot the distal end 6424 and/or proximal end 6426 thereof. The first weld6418 may be continuous or it may be discontinuous or intermittent.

The efficient force to fire (FTF) profile of the example 6458 can befurther improved, as indicated in the example 6460, by employing afiring control program, which can be selected at 6038 (FIG. 17), incombination with the stiffer anvil 6410. Any of the firing controlprograms associated with the previously described examples 6108, 6110,6208, or 6210 can be employed with the stiffer anvil 6410 to yield amore efficient force to fire profile. In the aspect of the example 6460,the stiffer anvil 6410 is combined with a firing control program thatruns the I-beam 2514 at a faster velocity initially followed by a slowervelocity when thicker tissue is encountered. The combination of thestiffer anvil 6410 and the firing program can yield a shorter time (t₁)to a maximum force to fire (FTF) relative to corresponding times (t₂),(t₃) of the examples 6456 and 6458. In addition, the combination canyield a shorter time (t4) to the stroke end position 2528 (FIG. 13) ofthe firing stroke relative to corresponding times (t₅) and (t₆) of theexamples 6456 and 6458. As illustrated in the diagram 6450, thecombination yields an additional 20% reduction in the maximum (FTF)compared to the maximum (FTF) of the example 6458. In some examples, theselected firing control program is configured to reduce the velocity ofthe I-beam 2514 in a first portion of the firing stroke by about onethird relative to the velocity employed in connection with the example6458.

The functions or processes 6030, 6111, 6131 described herein may beexecuted by any of the processing circuits described herein, such as thecontrol circuit 700 described in connection with FIGS. 5-6, the circuits800, 810, 820 described in FIGS. 7-9, the microcontroller 1104 describedin connection with FIGS. 10 and 12, and/or the control circuit 2510described in FIG. 14.

Various aspects of the subject matter described herein are set out inthe following numbered examples:

Example 1

A surgical instrument, comprising: a displacement member; a motorcoupled to the displacement member, the motor operable to translate thedisplacement member; a control circuit coupled to the motor; and aposition sensor coupled to the control circuit; wherein the controlcircuit is configured to: receive a position output of the positionsensor indicative of at least one position of the displacement member;and control velocity of the motor to translate the displacement memberat a plurality of velocities corresponding to the position output,wherein each of the plurality of velocities is maintained in apredetermined zone.

Example 2

The surgical instrument of Example 1, wherein the control circuit isconfigured to maintain the translation of the displacement member at afirst velocity in a first zone and a second velocity in a second zone,and wherein the second zone is distal to the first zone.

Example 3

The surgical instrument of Example 2, wherein the second velocity isgreater than the first velocity.

Example 4

The surgical instrument of Example 3, wherein the control circuit isconfigured to maintain the translation of the displacement member at athird velocity in a third zone, and wherein the third zone is distal tothe second zone.

Example 5

The surgical instrument of Example 4, wherein the third velocity isgreater than the second velocity.

Example 6

The surgical instrument of Example 2 through Example 5, furthercomprising a timer circuit coupled to the control circuit, wherein thetimer circuit is configured to measure time elapsed during translationof the displacement member to a predetermined initial position.

Example 7

The surgical instrument of Example 6, wherein the control circuit isconfigured to determine the first velocity based on the time elapsedduring translation of the displacement member to the predeterminedinitial position.

Example 8

The surgical instrument of Example 1 through Example 7, furthercomprising an end effector comprising a staple cartridge housing aplurality of staples, and wherein the translation of the displacementmember from the proximal position to the distal position causes thestaples to be deployed from the staple cartridge.

Example 9

The surgical instrument of Example 1 through Example 8, wherein thecontrol circuit is configured to determine the first velocity based onforce or current experienced by the motor.

Example 10

A surgical instrument, comprising: a displacement member; a motorcoupled to the displacement member, the motor operable to translate thedisplacement member; a control circuit coupled to the motor; and aposition sensor coupled to the control circuit; wherein the controlcircuit is configured to: receive a position output of the positionsensor indicative of at least one position of the displacement member;and drive the motor to translate the displacement member at adisplacement member velocity corresponding to the position of thedisplacement member.

Example 11

The surgical instrument of Example 10, wherein the control circuit isconfigured to increase the displacement member velocity at a linear ratefrom a starting velocity.

Example 12

The surgical instrument of Example 11, further comprising a timercircuit coupled to the control circuit, wherein the timer circuit isconfigured to measure time elapsed during translation of thedisplacement member to a predetermined initial position.

Example 13

The surgical instrument of Example 12, wherein the control circuit isconfigured to determine the starting velocity based on the time elapsedduring translation of the displacement member to the predeterminedinitial position.

Example 14

The surgical instrument of Example 10 through Example 13, furthercomprising an end effector comprising a staple cartridge housing aplurality of staples, and wherein the translation of the displacementmember from the proximal position to the distal position causes thestaples to be deployed form the staple cartridge.

Example 15

The surgical instrument of Example 10 through Example 14, wherein thecontrol circuit is configured to determine the first velocity based onforce or current experienced by the motor.

Example 16

A surgical instrument, comprising: a displacement member; a motorcoupled to the displacement member, the motor operable to translate thedisplacement member; a control circuit coupled to the motor; and aposition sensor coupled to the control circuit; wherein the controlcircuit is configured to: receive a position output of the positionsensor indicative of at least one position of the displacement memberalong the distance between the proximal position and the distalposition; and drive the motor at a plurality of duty cyclescorresponding to the position output, wherein each of the plurality ofduty cycles is maintained in a predetermined zone between the proximalposition and the distal position.

Example 17

The surgical instrument of Example 16, wherein the control circuit isconfigured to drive the motor at a first duty cycle in a first zone anda second duty cycle in a second zone, and wherein the second zone isdistal to the first zone.

Example 18

The surgical instrument of Example 17, wherein the second duty cycle isgreater than the first duty cycle.

Example 19

The surgical instrument of Example 18, wherein the control circuit isconfigured to drive the motor at a third duty cycle in a third zone, andwherein the third zone is distal to the second zone.

Example 20

The surgical instrument of Example 19, wherein the third duty cycle isgreater than the second duty cycle.

Example 21

The surgical instrument of Example 17 through Example 20, furthercomprising a timer circuit coupled to the control circuit, wherein thetimer circuit is configured to measure time elapsed during translationof the displacement member to a predetermined initial position.

Example 22

The surgical instrument of Example 21, wherein the control circuit isconfigured to determine the first duty cycle based on the time elapsedduring translation of the displacement member to the predeterminedinitial position.

Example 23

The surgical instrument of Example 16 through Example 22, wherein thecontrol circuit is configured to determine the first velocity based onforce or current experienced by the motor.

The invention claimed is:
 1. A surgical instrument, comprising: adisplacement member; a motor coupled to the displacement member, themotor operable to translate the displacement member through a pluralityof zones, wherein each one of the plurality of zones is defined by arange of displacement of the displacement member; a control circuitcoupled to the motor; a position sensor coupled to the control circuit;and a timer circuit coupled to the control circuit, wherein the timercircuit is configured to measure time elapsed during translation of thedisplacement member to a predetermined initial position; wherein thecontrol circuit is configured to: receive a position output of theposition sensor indicative of at least one position of the displacementmember; determine a zone within the plurality of zones in which thedisplacement member is located based on the position output of theposition sensor; set velocity of the motor based on the zone in whichthe displacement member is located, wherein a different velocity of themotor is set in each one of the plurality of zones; and maintain the setvelocity of the motor in the zone until the displacement member enters anew zone.
 2. The surgical instrument of claim 1, wherein the controlcircuit is configured to maintain the translation of the displacementmember at a first velocity in a first zone and a second velocity in asecond zone, and wherein the second zone is distal to the first zone. 3.The surgical instrument of claim 2, wherein the second velocity isgreater than the first velocity.
 4. The surgical instrument of claim 3,wherein the control circuit is configured to maintain the translation ofthe displacement member at a third velocity in a third zone, and whereinthe third zone is distal to the second zone.
 5. The surgical instrumentof claim 4, wherein the third velocity is greater than the secondvelocity.
 6. The surgical instrument of claim 2, wherein the controlcircuit is configured to determine the first velocity based on the timeelapsed during translation of the displacement member to thepredetermined initial position.
 7. The surgical instrument of claim 2,wherein the control circuit is configured to determine the firstvelocity based on force or current experienced by the motor.
 8. Thesurgical instrument of claim 1, further comprising an end effectorcomprising a staple cartridge housing a plurality of staples, andwherein the translation of the displacement member from a proximalposition to a distal position causes the staples to be deployed from thestaple cartridge.
 9. A surgical instrument, comprising: a displacementmember; a motor coupled to the displacement member, the motor operableto translate the displacement member through a plurality of zones,wherein each one of the plurality of zones is defined by a range ofdisplacement of the displacement member; a control circuit coupled tothe motor; a position sensor coupled to the control circuit; and a timercircuit coupled to the control circuit, wherein the timer circuit isconfigured to measure time elapsed during translation of thedisplacement member to a predetermined initial position; wherein thecontrol circuit is configured to: receive a position output of theposition sensor indicative of at least one position of the displacementmember; determine a zone within the plurality of zones in which thedisplacement member is located based on the position output of theposition sensor; set velocity of the motor to drive the motor totranslate the displacement member at a displacement member velocitybased on the zone in which the displacement member is located, wherein adifferent velocity of the motor is set in each one of the plurality ofzones; and maintain the set velocity of the motor in the zone until thedisplacement member enters a new zone.
 10. The surgical instrument ofclaim 9, wherein the control circuit is configured to increasedisplacement member velocity at a linear rate from a starting velocityuntil the set velocity for the zone is obtained.
 11. The surgicalinstrument of claim 10, wherein the control circuit is configured todetermine the starting velocity based on the time elapsed duringtranslation of the displacement member to the predetermined initialposition.
 12. The surgical instrument of claim 10, wherein the controlcircuit is configured to determine the starting velocity based on forceor current experienced by the motor.
 13. The surgical instrument ofclaim 9, further comprising an end effector comprising a staplecartridge housing a plurality of staples, and wherein the translation ofthe displacement member from a proximal position to a distal positioncauses the staples to be deployed form the staple cartridge.
 14. Asurgical instrument, comprising: a displacement member; a motor coupledto the displacement member, the motor operable to translate thedisplacement member through a plurality of zones, wherein each one ofthe plurality of zones is defined by a range of displacement of thedisplacement member; a control circuit coupled to the motor; a positionsensor coupled to the control circuit; and a timer circuit coupled tothe control circuit, wherein the timer circuit is configured to measuretime elapsed during translation of the displacement member to apredetermined initial position; wherein the control circuit isconfigured to: receive a position output of the position sensorindicative of at least one position of the displacement member along adistance between a proximal position and a distal positon; determine azone within the plurality of zones in which the displacement member islocated based on the position output of the position sensor; set dutycycle of the motor based on the zone in which the displacement member islocated, wherein a different duty cycle of the motor is set in each oneof the plurality of zones; and maintain the set duty cycle of the motorin the zone until the displacement member enters a new zone.
 15. Thesurgical instrument of claim 14, wherein the control circuit isconfigured to drive the motor at a first duty cycle in a first zone anda second duty cycle in a second zone, and wherein the second zone isdistal to the first zone.
 16. The surgical instrument of claim 15,wherein the second duty cycle is greater than the first duty cycle. 17.The surgical instrument of claim 16, wherein the control circuit isconfigured to drive the motor at a third duty cycle in a third zone, andwherein the third zone is distal to the second zone.
 18. The surgicalinstrument of claim 17, wherein the third duty cycle is greater than thesecond duty cycle.
 19. The surgical instrument of claim 15, wherein thecontrol circuit is configured to determine the first duty cycle based onthe time elapsed during translation of the displacement member to thepredetermined initial position.
 20. The surgical instrument of claim 15,wherein the control circuit is configured to determine the first dutycycle based on force or current experienced by the motor.